Caesar and the Roman Murders

Question

Caesar was quietly sipping a good cup of coffee at a cafe in Rome when a police officer suddenly approached him. We need you, (s)he said! We have a very complicated case and the primary victims here are important. Caesar, a great detective, was intrigued by the word "complicated" and agreed to help.

The police officer said that they collected video recordings of each victim showing the last thing of what they were doing and where they were before the crime was committed.

First Victim

Caesar went to the first victim. He is floating on the swimming pool, eyes wide open and seems to be looking into the sky. A piece of paper is lying beside him and there is a note saying: "I've waited a century just to kill him. Want a clue? The victim is the clue now because of me.". Caesar thought that this is the suspect's clue and he believes that the victim trusts the suspect and was loyal to him until now.

Caesar decided to look at the video recording. The victim is drinking at the Topaz bar not far from the crime scene. A stranger approached him and they talked for a few minutes. After that the victim left. The guy beside the stranger followed the victim.

Second Victim

Caesar then visited the second victim. He decided to look at the recording first.

The recording shows that the second victim is with a female stranger. They seem to be talking and are buying roses at the flower shop. After that, the victim left and the female stranger followed him.

Caesar then went to the crime scene and saw the roses on top of the victim. The roses are soaked in blood and a note is on top of it.

The note says: "On the start of the day I met you, I'm with you until the end, but I will also show you the end. Nothing will change if I'm still with you" Caesar was left with deep thoughts. It's like watching 500 Days of Summer. He believes that the suspect is the female stranger on the recording, might be a love affair angle.

Third Victim

Caesar hurried to the last crime scene, he immediately played the recording.

The recording shows the victim talking to two guys. Caesar was surprised to see the same guy from the first victim's recording! And what is surprising is the guy has a twin! In the recording, the victim handed a gold bar to the twins and left.

When Caesar checked the crime scene, he saw the gold bars on top of the victim's dead body, A Donovan music CD and a note was also there. It says: "1k of Gold only for me? because of that 'I'm the guy who can calm you down'. Thanks to the twins and I got the truth". Caesar concluded that this one might be jealousy.

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With all the clues and recordings, Caesar finally got the suspects and arrested them.

What you need to find out

1. The 3 suspects
2. The 3 victims

BONUS:

3. The name of the group of the 3 suspects

HINT:

Clues are distributed in the story. Using music, symbolism, words, movies. What is common on them. (second clue tomorrow if not solved)

adding more HINTS

The answers are not exactly a name. Italicized some words and phrases as clues

Answer 1

Well. Rome again is it.

First victim:
victim clues: pool, sky, clue, "loyalty" angle
suspect clue: century
pools and skies are blue, blue is a color associated with loyalty and "blue" impacted by the letter C (Roman numeral for 100, the number of years the suspect has been waiting) gives us "clue"

Second victim:
victim clues: roses, blood, "love affair" angle
suspect clue: (500) Days of Summer
roses and blood (and love) are red, and "red" impacted by the letter D (Roman numeral for 500, the number of Days of Summer) gives us "de[a]d". At the start of the day that I met you, indeed.

Third victim:
victim clues: gold bars, Donovan lyrics, "jealousy" angle
suspect clues: "1K of gold"
gold (and jealousy) is effectively yellow, and yellow conveniently appears in the title of the song to which the quoted lyrics belong, Mellow Yellow (quite rightly). "1K" is a very Greek way of saying what a Roman might call "M". "Yellow" impacted by the letter M gives us "Mellow". It seems M was in fact the guy who could calm Yellow down.

per OP:
'"On the start of the day I met you, I'm with you until the end, but I will also show you the end. Nothing will change if I'm still with you" is letter D. Start of (D)ay and with you until the en(D) and nothing will change because D is in the color RED.'

and also
'And for the twins, they are the letter L. Appears in BLUE and and YELLOW. And lastly, Topaz is associated with Blue'

We've been told at the very beginning of the story that Caesar is being asked to investigate the primary victims.

Well, it turns out these are not "primary" because there are other victims; they are primary colors: blue, red, and yellow. The suspects? Murderous, murderous numbers masquerading as letters.

Special thanks to @GentlePurpleRain for helping me brainstorm this in chat, especially noting the transformation of the color words caused by the Roman numerals. Luckily for him, purple isn't a primary color.