Police investigating five fatal shootings in California believe a serial killer may be on the loose in the state.
Detectives released a grainy image of a “person of interest” following the latest killing shortly before 2am on Tuesday.
Surveillance footage showed a man in black with a black hat behind him.
Stockton police said they could be suspects or witnesses.
Offers totaling $85,000 (£76,000) for information leading to arrests following the shooting.
Stockton Police Chief Stanley McFadden said the latest victim was a 54-year-old man who was shot in a residential area.
He is the fifth person to be shot and killed within a few square miles of Stockton since July 8.
Mr McFadden also detailed each attack that occurred.
• July 8 – An unidentified 35-year-old man was shot dead at 12:31 am.
• August 11 – An unidentified 43-year-old Hispanic man was killed at 9:49 pm
• August 30 – An unidentified 21-year-old Hispanic man was shot dead at 6:41 am
• September 21 – An unidentified 52-year-old Hispanic man was killed at 4:27 a.m.
• September 27 – An unidentified 54-year-old Hispanic man was shot and killed around 1:50 a.m.
“Stay vigilant – keep your head spinning”
Mr McFadden said he believed all five homicides were related “based on our investigation and the reports we received”. All the victims walked alone when they were killed.
Stockton is a city of 320,000 residents located approximately 50 miles (80 kilometers) south of the state capital, Sacramento.
Mr McFadden said police had ruled out gang violence, hate crimes and targeting homeless residents, and detectives could not determine whether there was one or more shooters.
The police chief wrote on Facebook: “We are committed to protecting our communities and solving these cases, using all resources, including yours. We need your help!!! If anyone has information about these investigations, please call immediately us.
“Remember that our victims have grieving families to address. If you know something, say something.”
Mr McFadden added that the killing took place in a “dimmed” area “shaded by trees”.
“Stay vigilant,” he said. “Put your head on the turntable.”
The City of Stockton is offering a reward of $75,000 (£67,000), with an additional $10,000 (£8,884) from Stockton Crime Stoppers.