Mollie Tibbetts' Surprising Connection to Her Alleged Killer's Ex-Girlfriend

Cristhian Rivera is charged with first-degree murder.

Slain college student Mollie Tibbetts attended school with her accused killer's ex-girlfriend.

Iris Monnarez, who has a 3-year-old daughter with suspect Cristhian Rivera, 24, is believed to have lived in a red trailer on the farm where Rivera worked until they broke up last year. 

Monnarez was just one grade above Tibbetts at their high school in Brooklyn, Iowa. 

The graduating classes at the school are very small, only about 40 students each. Monnarez was a cheerleader and Tibbetts was on the track team.

The two girls were also Facebook friends, but in a small town like Brooklyn, it's unclear if they were really friends.

Tibbetts' death is now front and center in the national debate on immigration with President Trump calling for tougher laws in the wake of her death. 
Authorities said Thursday that Tibbetts died of multiple sharp-force injuries. Her body was found Tuesday, nearly five weeks after she vanished on July 18.

Tibbetts' funeral will be held on Sunday at the high school's gymnasium.