A man suspected of killing six men and wounding a woman in a series of shootings in Northern California has a criminal history that includes traffic violations and convictions for drug crimes, authorities said Monday.

Stockton police arrested Wesley Brownlee, 43, on Saturday after surveilling him as he drove through the streets of the city, armed with a handgun and possibly searching for another victim, police said.

In January 1999, Brownlee was sentenced to two years in prison in Alameda County for possessing and selling a controlled substance, the California corrections department said. He was released on parole in August 1999 after serving seven months.

Brownlee was again convicted in Alameda County in December 2001 and sentenced to three years for the same crime. He was released to parole in May 2003 and was discharged from parole three years later.

Public records from San Joaquin County show Brownlee has two traffic violations in 2021 and 2022, along with a felony in 2017 and a DUI in 2009, KCRA-TV reported.

San Joaquin County prosecutors worked Monday with the Stockton Police Department to review the evidence and expect to file charges Tuesday, said Elisa Bubak, a spokesperson for the San Joaquin County prosecutor’s office.

It was not immediately known if Brownlee has an attorney who can comment on his behalf.

Police said after Brownlee’s arrest that he was dressed in black, had a mask around his neck and a handgun, and “was out hunting” for another possible victim when he was arrested while driving around the Central Valley city, where five men were ambushed and shot to death between July 8 and Sept. 27. Four were walking, and one was in a parked car.

Police believe the same person was responsible for killing a man 70 miles (110 kilometers) away in Oakland in April 2021 and wounding a woman in Stockton a week later.

Investigators have said ballistics tests and video evidence linked the crimes. A police photo showed the black and gray weapon allegedly carried by the suspect. It appeared to be a semi-automatic handgun containing some nonmetallic materials.

At Saturday’s news conference, a moment of silence was held for the victims.

Juan Vasquez Serrano, 39, was killed in Oakland on April 10, 2021, and Natasha LaTour, 46, was shot in Stockton on April 16 that year but survived. The five men killed in Stockton this year were Paul Yaw, 35, who died July 8; Salvador Debudey Jr., 43, who died Aug. 11; Jonathan Hernandez Rodriguez, 21, who died Aug. 30; Juan Cruz, 52, who died Sept. 21; and Lawrence Lopez Sr., 54, who died Sept. 27.

After receiving hundreds of tips, investigators located and watched the place where Brownlee was living. They watched his patterns, determined he was out searching for another victim and arrested him, authorities said.

Police said some victims were homeless, but not all. None were beaten or robbed, and the woman who survived said her attacker didn’t say anything.