Victim's sister requests a Pardon for Dan Sanders, since the police refused to follow other leads in the case

Dan Sanders was kept in jail for more than 14 months in 2008, without a trial, pressured to sign a manslaughter confession by the police, who scared him with the death penalty if he went to trial. Dan, a teenager at the time of the arrest, had never been in jail, and had no history of violence. The police did not follow up on any of the victim's psychiatric patients, instead arresting the victim's son(Dan). These patients were never followed up by the police, due to the privacy rights of the patients,even the violent ones. I am the victim's sister, and I don't believe Dan killed my sister. Dan, in prison since 2008, is serving 19 years. If he did commit manslaughter, 19 years is too long, for an accident. Please help me by signing the petition.
Mercy is powerful. Thank you!