Murder Mystery. Who is the killer?

Question

There is a riddle about a Murder Mystery.

My friend, who is studying law, gave me this puzzle. It was originally given to him by his professor, who often gives puzzles to his students.

There are 7 suspects: Sister, Brother, Mother, Grand Mother, Father, Grandfather and Cook.

Question: Who is the killer of the eldest son and what method did the killer use to kill?

Here are the testimonies of each suspect.

Sister

My poor brother. I can’t believe he’s dead. Just yesterday we were discussing closing another big deal which could do wonders for the future of the company.

My last 24 hours? Working. I am always working. I was at the office all day, keeping an eye on things and doing my job. I have no idea where my brother was, but dad had asked us both to be at the office as he was working from home. A creature of habit? Yeah, you could say he was a creature of habit. He liked everything to be done his way, but he didn’t like to do any of it himself. He would delegate to everyone else, and then go “networking”. This dynamic worked great for me, I am more of a behind the scenes person, while my brother is…was…much more of a boys-boy people person who could close deals with bigwigs. I got home some time in the evening and overheard my father and grandfather arguing in the study. Something about the detriment of the company. All I know is that my grandfather was NOT happy about the decisions of my father. I decided to get out of the house and go visit my younger brother who was at the stables. I helped feed the horses and felt very relaxed out there. I really should go out there more often, but work has overtaken my life as of late.

This morning? After discussions with my older brother yesterday, I wanted to make sure everything was all ready for that deal we were closing and so I went into work early to sort out any paperwork we might need. I saw my father, and he told me my brother had died! We travelled home together, but I couldn’t believe it until I saw him myself. I feel absolutely devastated at his loss, who would do such a thing?!

Grandmother

My poor grandson! No one deserves to be murdered!

What was I doing for the last 24 hours? Well let me think. Yesterday, I was out helping with the horses in the morning. I do love spending time with my youngest grandchild. Especially since I know he misses spending time with his siblings. They aren’t as close now as they used to be, you know. He and his sister used to go riding together all the time, but now she works so hard for the family business she has no time! And the eldest, oh how he flitted around. So set in his ways, just like his father. He knew he was going to get the business, you know. My husband was not overly thrilled at this. He believes it should go to our granddaughter instead. But never mind that. I remember having a conversation with the cook. I haven’t had my favourite lunchtime scones in a while, and knew she was going to the markets so wanted her to pick up supplies to make them. Then I spent some time in the garden. I knew my daughter-in-law was going to be bringing back some flowers from her Horticulture Society meeting and so wanted to make sure there was ample room for them. She loves that garden, will hardly let anyone near it!

This morning, I noticed someone moving around in the upstairs bathroom earlier than usual. My grandson, very set in his ways as I mentioned earlier. He would usually brush his teeth and drink some mouthwash around 7:30, just before going downstairs for breakfast, but someone was in there around 7. Strange, but I guess maybe someone just needed to use the bathroom. By the time I made it downstairs for breakfast, around 8:35, my grandson was dead!

Brother

I knew my brother was making poor choices, I can’t believe he actually died though! We hadn’t been as close as we used to be, and thinking back now, I wish we had spent more time together when we had the chance.

What was I doing for the last 24 hours? What I always do. Tending to the horses. I love those horses, and spend every moment I can training and caring for them. Which reminds me, I need to get a new lock for the medicine cabinet in the stables. Why? Well, I guess it doesn’t matter so much now, but I caught my brother stealing from it. He was supposed to be at work, but as usual he was skiving off and well, let's just say if mum and dad knew what their golden child typically did during work hours, then he wouldn’t have been getting the family business. The firm should be going to my sister, who actually works hard. I miss how much fun we used to have riding horses, but now work has overtaken her life and I don’t ever get to spend any real time with her.

Where was I? Oh yes, yesterday. I was with the horses. My Grandmother was helping me brush them, and then I had to go and make myself lunch. The cook used to do it, but now she just prepares breakfast and dinner, and has things readily available for lunch. I don’t know what she does with her time if not cook! In the evening, my sister must’ve heard about the promotion and came out to help me feed the horses dinner. She only really comes and spends time with me out here now when she needs a break, and it makes sense that this news would lead her to come out here. It was nice, if not a little sad. This morning, I got up to go ride the horses as I usually do, but stayed completely downstairs as I don’t like going back upstairs as to not disturb anyone early in the morning. I brushed and fed all 5 horses, and took them all out for a quick ride. When I eventually got back inside for breakfast, around 8:45, my brother was dead. I wish we had more time together. I guess life really does get in the way!

Father

I feel distraught that my son, my heir, has been killed. He was supposed to be promoted this week to take over the family business! Now the Accounting firm my father built from the ground up is going to be left to a boy obsessed with horses and a girl. I mean I love my daughter, but she’s lucky I even let her work there. This kind of work isn’t cut out for a girl.

The last 24 hours? Well, yesterday I was working from home, as I trusted my children to be in the office to take care of things. I had a meeting with my father at some point in the evening regarding the promotion of my son, but he really has no idea about what goes on at the firm anymore. My wife was out of the house most of the day yesterday, out with her Horticulture Society I believe. My youngest was riding and caring for the horses. What about the cook? I believe she was hanging around the house, too. She came into my study at one point, otherwise she was doing a stocktake to go to the markets this morning.

This morning, I came home from the office as soon as I heard. My daughter was at the office slightly earlier than usual, but she is always pottering around doing odd jobs. My eldest son is the real creature of habit. Always takes the same breakfast at the same time in the same place. 8am, pancakes and black coffee, in the front room. He then is at work at 9am on the dot, except for today. I thought it was odd, that's when I got the phone call. It’s too much for me to bear!

Cook

Oh my days! Dead?! I just made his breakfast this morning! How sudden!

Yesterday? Well, I made the family breakfast as I always do. The eldest boy always take his breakfast in the front room at the same time, and so I know to get that ready on time. I then started to stocktake the food in the home. The grandmother asked me to get the supplies for scones, as she has been missing them of late. In the afternoon, I accompanied the man of the house in his study. I glimpsed the eldest boy through the crack in the door while in there. It was odd to see him at home, as I thought he was at work and the house was empty. In the evening, I prepared dinner as usual and then retreated to my room.

In the morning, I rose early, saw the youngest boy out to the horses, and made breakfast as usual. My chore for the morning, as I mentioned earlier, was to go to the markets. I was not long there before I heard of the young master’s demise. How unfortunate for him to be struck down at such a young age.

Grandfather

The poor, stupid boy. If he took better care of himself, who knows if he would still be here to this day.

Murdered? Really? I assumed he had overdosed on those damn drugs. I told my son he was not fit to run the company I had worked so hard to build. The last 24 hours? I spent the majority of my time doing as I usually do, wandering the grounds. I take a good book with me, currently I am reading Shakespeare. Hamlet has been quite intriguing. Such a classic. I found a comfortable spot under a tree and saw my eldest grandson skulking around. I found this strange, as I believed he was supposed to be at work. I later on discussed with my son the suitability of him being the next in line to take over the company. My son insisted that I had no idea the goings on at the firm and I should mind my business! The nerve! Its almost as if no one in this house has any idea what is going on. That is the benefit of being retired I supposed. I have the leisure to wander as I please, and see more than most.

This morning I rose earlier than usual and took a stroll around the grounds. I saw cook up and about, and my youngest grandson going out to the horses. I can’t believe the young man has kicked the bucket. What a sorry loss for our family.

Mother

I can’t believe my sweet, darling boy is dead! My perfect oldest son! He had so much potential! He was just about to be promoted, don’t you know! My angel boy, the third generation of men to run the family business!

The last 24 hours? Oh I don’t know, let me think. Oh yes, thats right. Yesterday was our fortnightly meeting of the Women’s Horticulture Society! What is the Women’s Horticulture Society? Oh, that is not a silly question at all! The Women’s Horticulture Society are a group of like-minded ladies who love to garden! I spend the majority of my time in my greenhouse. I have a special interest in exotic plants. I know all the different breeds and varieties, and yesterday was lucky enough to bring home a new one! You can see it from the window here. See? The one with purple flowers? Yes! My mother-in-law helped plant them. She is the only one who I let anywhere near my garden.

This morning I got up after my husband had already made his way into the office, and noticed that my daughter had also already left. I knew I wouldn’t see my youngest son for breakfast until 8:45, and so joined my oldest in the front room where he always is. The cook had left to go to the markets bright and early after bringing my oldest his pancakes. Partway through breakfast, I saw my darling son collapse headfirst into his food. I called the ambulance and police, and then my husband to hurry home. My youngest son was back inside after being with the horses. You can always tell he has been out there, as he smells of horse and has mud on his pants. I can’t believe my sweet son died in front of me. What an atrocious thing for a mother to witness!

EDIT: The professor said the answer (given by the SteveV below) is not 100% correct. Here is what he said "I really like this guess as some of the inspiration was related. Keen eye"

Answer 1

I think it was

the grandfather

because

motive: Knew eldest on drugs, skipping work and not suitable to run HIS business

means: his wife brought home a purple flowering plant, probably wolfs bane. A highly poisonous plant that Romans used to poison arrow and spear tips. Also, Laertes used it in Hamlet (which grandfather was reading) which may have give him the idea

opportunity: No one saw him that morning (but everyone else was seen). He could have gone to the bathroom upstairs and poisoned his mouthwash or razor.

Answer 2

I think it was

the sister

motive:

in the younger brother's testimony, "In the evening, my sister must’ve heard about the promotion...". She even admitted that she "overheard her (my) father and grandfather arguing in the study."

means:

she knows (probably learned from the younger brother) that her elder brother has been stealing drugs from the medicine cabinet in the stables. she went (in the excuse of needing a break) and stole the same drug in the evening and planned to let him overdose it the next morning.

opportunity:

she woke up earlier than usual, went into the bathroom on the first floor just before her brother (7am) and added the drug to his mouthwash. The drug, if not overdosed, won't affect anyone else.

deduction:

Usual activities: Younger Brother tended to horses as seen by Cook and Grandfather. Cook went to the market as seen by Mother. Father left for work before Mother woke up. Mother joined Older Brother breakfast. Grandmother stayed inside room and heard unusual activities at 7am.

Unusual activities: Sister and Grandfather both rose earlier than usual. Only the Sister knows about the medicine cabinet.

Answer 3

I believe it was

the grandmother

Here is my chain of thought

Let's start by thinking about the possible reasons of his death. Considering the fact that he died suddenly with his mother as the witness (assumed true for now) and taking into account his strict routine, the most plausible reason appears to be an overdose of his drug.

Now from the younger brother's statement, we know that the elder brother had the drug stored in the medicine cabinet and we also know that it wasn't locked. This is another strong indicator which supports the hypothesis. This points to a few people who had visited the stables in the previous 24 hours, the sister, younger brother, and the grandmother.

The grandmother is the one who very clearly knew the entire routine of the elder brother with the exact times and she had talked with her husband about the elder brother being unfit for an heir. The grandfather knew about the drugs and could have possibly told his wife about them. It can also be seen that the grandparents' room was just adjacent to the first floor bathroom.

The younger brother seems to have been constantly under someone's vision throughout and the sister's story corroborate's with the father's version thus making them less suspicious. The grandmother meanwhile doesn't seem to have been under much supervision.

What the scenario possibly could have been

The grandmother was out with in the stables with the younger brother under the pretext of helping him. She had already ensured the absence of the cook by instructing her to go to the market for ingredients for her scones, thus practically vacating the ground floor. The brother had to leave to make lunch since the cook wasn't there. Therefore the grandmother was left alone in the stables from where she stole the drug. She then proceeded to poison his mouthwash at 7 am because she knew he "drank" the mouthwash and didn't spit it out. This overdose of drug could have easily shown effects within the next 2 hours approximately.

Some final thoughts

The grandmother waiting outside in the garden also raises suspicion, almost as if she was standing guard.

I really liked SteveV's answer and initial suspicions do rise towards the grandfather but I personally did not see much supporting evidence against him.

One thing which I didn't understand in the problem was a statement in the brother's testimony - "She only really comes and spends time with me out here now when she needs a break, and it makes sense that this news would lead her to come out here." How did the brother assume that the news of the death led the sister to come outside when the death hadn't occurred?

Answer 4

I think it might have been:

the Cook

My train of thought:

After I posted my original answer, I've noticed that the question has been tagged with logical-deduction and liars. I could quickly explain the logical deduction I used with the updated answer. As for the liars, I failed to come up with a story where the liars' lie would mean something significant to the case, until now.

Liars:

Father and Cook

Reasoning:

Father drove both the Sister and the Eldest Brother away from home, because he had to work from home.

Cook joined Father in the study in the afternoon, expecting no one else to be at home. She "glimpsed the eldest boy through the crack in the door while in there."

I can't personally recognize anyone passing through the hallway from a crack in the door. But I can certainly at least hear which door has just been opened/closed on the same floor.

So I bet the study was not where the only place they stayed. A logical guess would be the Parent's Bedroom. That's where the Cook saw the eldest son. And they might have been seen by the eldest boy as well.

Motive:

the eldest brother blackmailed the pair for a promotion

hence, the sudden argument between Father and Grandfather

Method:

food poisoning

I just don't see how either of them know about the drug the Eldest Brother had been using though, so it might not have been drug overdose in this case.