Updated

Authorities identified a man whose dismembered body was found scattered around San Diego this week as a 57-year-old transient, and they arrested an acquaintance early Thursday on suspicion of murder.

Gerald Michael Nash, 61, who knew the victim, had not been formally charged but was in custody, Police Sgt. Kerry Tom said.

Detectives were still trying to determine a motive for the shooting and dismemberment of Allen Burton Hawes, Lt. Jeff Sferra said.

Hawes was shot to death sometime after Feb. 23, when he was seen on a surveillance camera in a supermarket checkout line, police said.

On Monday, his torso was found floating in the Otay River. Early Tuesday morning, a tow-truck driver discovered a head in a trash bag off Interstate 5, and a few hours later, a freeway crew found a hand on the side of a road about 3 miles away. Both are believed to be from Hawes' body.