A cellphone left at the scene of a southwest Santa Rosa killing helped detectives tie four men to the slaying, prosecutors said Tuesday.

The high-tech break came in last year's slaying of Jose Manuel de Jesus, 33, of Santa Rosa, whose body was found in the trunk of a car parked outside the Carniceria Contreras on Todd Road.

Prosecutor Juliette Olson told jurors deciding the fate of the defendants that de Jesus was shot to death when he tried to sell marijuana to the men.

Detectives found his cellphone outside the car and used a GPS tracking device to locate phones he called just before the killing.

Olson said one belonged to Juan Ramon Lopez Castillo, 28, a clerk at the butcher shop who she said agreed to buy the pot. Another was linked to the phone of his brother, Fernando Lopez Castillo, 25, accused of the actual shooting, she said.

Further investigation led to the arrests of two others, their cousin, Alberto Lopez-Barraza, 33, of Hayward, and Jose Carraballa Mejias, 54 of Santa Rosa.

All are charged with murder during a robbery and face life in prison.