James Dolphs Elmore Jr. has been sentenced to 20 years in prison for his role in the 1986 death of 16-year-old Laura Miller, whose body was found in the area known as the “Texas Killing Fields.”

A jury convicted the 61-year-old Elmore of manslaughter after prosecutors accused him of preparing the cocaine dose that killed Miller.

Authorities said the cocaine was administered by Clyde Hedrick, whom investigators have linked to the deaths of several women whose bodies were discovered near Houston.

Hedrick died by suicide earlier this year before prosecutors could seek indictments against him in Miller’s death and other killings, ABC News has reported.

More than 30 girls and young women have been found dead in the Texas Killing Fields area since the 1970s, but most of the cases remain unsolved.