Seeking a murder mystery about drowned boy who was bullied probably published around 2000-2003, maybe up to 2005 this book was for high schooler and young adults and I think the cover was blue with a rose. The main story line of the book was an investigator was trying to find the cause of death of a teenage boy who was found in the river who they initially thought was a drowning but then found stool in his lungs that was his cause of asphyxiation. The river had once had a sewage issue, but that was investigated and found that the problem was fixed. He was accidentally killed by other students who gave him a swirly (dunked head into a toilet) that had stool in it that caused him to suffocate. The reason that he was given the swirly was he had a crush on a girl and had given her a rose he had changed the color of from red to (possibly) blue as a magic trick, the book did describe the chemical trick used to perform this. I do not remember the color of the rose, apologies. The girl’s bf or some other significant male figure.