BATON ROUGE - Deputies arrested a fourth family member, all accused of involvement in the killing of a man whose "mangled" body was found on the old Mississippi River Bridge.

New documents obtained by The WBRZ Investigative Unit detail what deputies say happened to 41-year-old Gerard Nicholas Richard and the coverup of his death afterward.

Deputies said 17-year-old Da'Sean Conley was beating Richard, his mother Coshelia Conley's boyfriend, inside an apartment in Baker that is lived in by his grandmother 55-year-old Cathy Conley on Feb. 13.

New documents show that 33-year-old Darius Conley was in the apartment and holding Richard at gunpoint as Da'Sean beat him. Deputies said both Darius and Da'Sean forced Richard into a vehicle in the parking lot where they shot and killed him.

Afterward, the Conley family reportedly tried to destroy evidence and dispose of the body. Richard was found dead, wrapped in a blanket with his hands tied and dropped off in the middle of the old Mississippi River Bridge. Deputies said there were blood smears on the railings as if someone tried to throw him over but dumped his body in the road when it didn't work.

Darius Conley was booked for first-degree murder, second-degree kidnapping and obstruction of justice.

Coshelia Conley was arrested for being an accessory after the fact of second-degree murder and obstruction of justice. Da'Sean Conley was booked for second-degree murder and obstruction of justice. Cathy Conley was booked for principal to second-degree murder and obstruction of justice.