CHICAGO (AP) – Federal prosecutors are seeking a 40-year prison sentence for man found guilty of sex-trafficking a Chicago teenager who was murdered.

Joseph Hazley was found guilty in March of sex-trafficking 16-year-old Desiree Robinson and two other victims. Robinson was allegedly killed in December 2016 by a man who answered an online sex advertisement.

READ MORE: 'John Doe' Who Accused Former Blackhawks Video Coach Brad Aldrich Of Sexual Abuse Identifies Himself As Kyle Beach

Desiree Robinson (provided photo)

Although Hazley wasn’t charged directly in Robinson’s death, prosecutors contend the case is a reminder of the danger faced by sex trafficking victims. In his filing, defense attorney Raymond Wigell wrote Hazley has mourned woman’s death.

READ MORE: Chicago Weather: Showers Coming Thursday

RELATED: Chicago man Convicted In Sex Trafficking Case Involving Murdered 16-Year-Old Girl

Antonio Rosales is awaiting trial on first-degree murder and aggravated sexual abuse charges in Robinson’s death.

MORE NEWS: View Live Radar

Copyright 2019 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.