BURLINGTON, Iowa (AP) — One of two cousins charged in the death of a gender-nonconforming Iowa teenager is set to go on trial. Attorney General Jeff Sessions has highlighted the case against 23-year-old Jorge Sanders-Galvez by taking the unusual step of assigning a federal prosecutor to assist state and local authorities in the case.

Sanders-Galvez and his cousin Jaron Purham are charged with first-degree murder in the March 2016 slaying of 16-year-old Burlington, Iowa, high school student Kedarie Johnson. Sanders-Galvez’s is set to start Tuesday. Relatives say Johnson was gender fluid, identifying as both male and female. A prosecutor says Sanders-Galvez tried to have sex with Johnson and became enraged after learning that Johnson was gender nonconforming.

Purham is expected to be tried later.