Updated

A California serial killer that Stockton police believe may be tied to at least six murders and an additional shooting since April 2021 is on the loose.

The suspect was initially accused of fatally shooting Paul Yaw, 35; Salvador Debudey Jr., 43; Jonathan Hernandez Rodriguez, 21; Juan Cruz, 52; and Lawrence Lopez Sr., 54, over the last three months, with the most recent murder taking place Sept. 27.

Police have since announced, however, that the suspect is linked to additional incidents that occurred in April, including the shooting of an unnamed 46-year-old Black woman in Stockton April 16, 2021, and the fatal shooting of an unnamed 40-year-old Hispanic man in Oakland April 10, 2021. Both shootings occurred in the early morning at 3:20 a.m. and 4:18 a.m., respectively. 

A $95,000 reward is being offered for information leading to an arrest in the case.

STOCKTON SERIAL KILLINGS: CALIFORNIA ‘PERSON OF INTEREST’ SPOTTED NEAR MULTIPLE MURDER SCENES, POLICE SAY

grainy images shows person of interest dressed in black; Map showing five possibly related murdersa

Police in Stockton, Calif., released a surveillance photo of the person of interest in five recent homicides. (Stockton Police Department/Facebook)

Each of the deceased victims was male and was alone at the time, Stockton Police Officer Joseph Silva confirmed to Fox News Digital, though they differ in age and other circumstances. One of the victims was shot while alone inside a vehicle, while the other four were alone outside at the time, Silva said. Four of the victims were Hispanic men, while the fifth was a White man.

Silva, the department’s public information officer, said all five murders were carried out in "very dark" areas.

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On Friday, Stockton Police officials released a grainy image showing their "person of interest" wearing what appeared to be dark clothing and a hat.

Map showing locations of five homicides

Stockton police share a map showing the locations of five recent homicides within the city. (Stockton Police Department/Facebook)

Joseph Giacalone, a criminal justice professor at John Jay College of Criminal Justice and a former law enforcement officer, said police will now try to see if there are similarities between current cases and previous ones, whether any criminals have been "recently released" and determine when the first homicide in this case occurred.

"Generally, your suspect lives really close to that first one because that's where he felt most comfortable," the former officer noted. "The only thing that's really concerning me now is that they're happening closer together."

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Silva told Fox News Digital Monday that investigators have been able to track the person of interest "near some of the crime scenes." He would not divulge more about the sightings. But he said investigators have not "caught anyone on video surveillance holding a gun or even committing a crime."

Now, the killer is "getting more and more confident," Giacalone said of the most recent string of shootings dating to July. "When they get more confident … the bodies tend to rack up faster."

Stockton Police vehicle

Stockton Police Chief Stanley McFadden notified the public of a startling pattern on Friday, shortly after being briefed by his detectives of the circumstances and similarities between each case. (Stockton Police Department)

Criminals "learn from the mistakes," and the suspect might even be "following this case in the media," he continued.

Stockton Police Chief Stanley McFadden notified the public of a startling pattern Friday, shortly after being briefed by his detectives of the circumstances and similarities between each case, according to Silva. In an announcement posted to Facebook, McFadden urged the public to remain vigilant as the manhunt continues

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"Please avoid isolated areas and travel in well-lit areas. Remember, there is safety in numbers. So if you can, travel with a friend," McFadden stressed. "If you see suspicious activity, call 209-937-8377 or 911 if it’s an emergency."

Stockton police are asking anyone with information to call (209) 937-8167 or email policetips@stocktonca.gov. Tipsters can also submit information anonymously to Stockton Crime Stoppers via its website or by calling (209) 946-0600.