Robbery was the motive behind last week’s bludgeoning death of a 68-year-old Gainesville man, with three teenage gang members from Athens suspected in his killing, authorities said Tuesday.

Nelson Vaca, 17, was the second person charged in the death of Ramon Hernandez, whose dead body was found Thursday morning in the trailer where he lived alone in the East Ridge Mobile Home Park off Marlow Drive. Vaca is charged with party to the crime of murder, Hall County Sheriff’s Col. Jeff Strickland said.

Vaca was picked up by investigators at an Athens manufacturing facility where he worked, Strickland said. Vaca is the cousin of Daniel Vilchis-Ayala, 16, who was arrested at his Athens home last week and charged with murder.

A third suspect, 16-year-old Brian Martin Rivera of Athens, is being sought on an outstanding murder warrant.

Strickland said all three teens are members of the SUR-13 street gang in Athens. Investigators believe Hernandez, who did maintenance work and other odd jobs at the trailer park, suffered blunt force trauma to the head during a robbery. Strickland declined to say why Hernandez might have been a target for robbery.

Investigators are still looking into whether the teens knew the victim.

“We’re still early in the investigation,” Strickland said.

Authorities have impounded a car belonging to the sister of Vilchis-Ayala which they believe was used during the robbery, Strickland said. He declined to comment on whether investigators have seized a suspected murder weapon.

Vaca remains in the Hall County Jail without bond. Vilchis-Ayala, who is technically a juvenile but was charged as an adult, is being held in the Gainesville Regional Youth Detention Center.

Rivera is believed to have fled the area to avoid arrest, Strickland said.

Anyone with information on his whereabouts is asked to call 770-531-6879.