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.

The 35-year-old Hazley, who awaits sentencing June 12, was the second person convicted in connection with Robinson's case. Charles McFee pleaded guilty last year to sex-trafficking conspiracy.

Although Hazley was not charged directly in Robinson's death , prosecutors contend the case is a stark reminder of the "constant state of danger" faced by sex trafficking victims. In his filing, defense attorney Raymond Wigell wrote Hazley has mourned woman's death.

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