Cannot believe this happened (kinda long)

So a little context, it was down to the final four. It was me(green), cyan, pink, and black. Pink was afk and cyan and black ran both left and right, I went down to admin where I saw a light on the security cameras, I saw someone go down through the bottom into electrical, then they went from electrical to med bay in an instant on the map( that’s when I knew that I could catch someone) I saw them go from med to security, and the blinking light on cams went out, so I went up through cafeteria( pink was still there) and found blacks dead body in security, I reported it and called out cyan. I described the entire process of me catching them, and then pink says that they are playing on two different phones and skips, then cyan just teases me by venting all around me, cyan waits until both me and his alt are almost done with tasks then calls a meeting, they threw so many insults and slurs at me and then voted me out. I am fuming at how people just blatantly cheat like that and still manage to not get kicked or banned from the server after the game.