τετέλεσται! welcome to Websleuths. I am not sure how much research you have done on this case, but I sense you may not be familiar with the Canadian justice system and how Canadian law enforcement agencies deal with information regarding crimes.
You make the statement "They can't even find evidence to solve this case". The Toronto Police Service, (TPS) the police agency that has jurisdiction and is doing investigation. Their goal is not necessarily to solve the case, but rather to bring the perpetrators to justice by means of the criminal judicial system. Secondly the TPS, as most Canadian law enforcement agencies, do not share with the public what evidence they do or do not have with the public prior to charges being laid and a trial is underway.
In fact the TPS may know who did it, but may not yet have enough evidence, to prove to a jury beyond a reasonable doubt of the perpetrators guilt. Understand in Canada there is no statute of limitations on crimes of murder, so there is no time limit to lay charges. Secondly chances are the prosecution will have to convince the jury, while likely the defense will be made up of the best lawyer(s) in Canada money can buy.
TPS and the prosecution will only have one chance to win the trial, and will make every effort to have an ironclad case.
Regarding your comment about Jonathon Sherman increasing the reward. Likely he would say 'to motivate someone to come forward with evidence that could lead to a conviction'.