Residents of Stockton, California breathed a sigh of relief when suspected serial killer Wesley Brownlee, 43, believed to be the Stockton Serial Killer, was captured by police. Now, authorities have found out that Brownlee used a ghost gun to commit his acts of murder.

According to NBC News, a ghost gun is a firearm that can be 3D printed without a federally mandated serial number. Because they are 3D printed, those who make them also skip background checks.

The case is now the first known serial murder case where the serial killer used a ghost gun, which can be used almost like burner phones, as they are disposable devices. Several cities have prohibited these weapons, with police and the Justice Department raising concerns about them because they allow anyone to skip legal checks for firearm ownership.

A "polymer" weapon was tied to several murders around Stockton. San Joaquin County District Attorney Tori Verber Salazar stated that they are confident that the gun they recovered from Brownlee was the same gun used in three homicides.

Police also announced that Brownlee was charged with three counts of murder on Tuesday. These murders were tied with the ghost gun authorities confiscated when they arrested him.

READ MORE: Suspected California Serial Killer Arrested Right Before He Made Another Kill, Police Say

Stockton Serial Killer Wesley Brownlee Arrested While 'On the Hunt'

According to the San Francisco Chronicle, residents of Stockton were on edge when news of a serial killer on the loose within their city broke. However, residents were finally able to rest easy when Police Chief Stanley McFadden announced Wesley Brownlee's arrest.

Police were on high alert during his crime spree, and when they saw a man exhibiting "threatening behavior," they followed him with a surveillance team. Finally, while driving in the area of Village Green Drive and Winslow Avenue on Saturday, they arrested him.

"As officers made contact with him, he was wearing dark clothing and a mask around his neck. He was also armed with a firearm when he was taken into custody," McFadden said during a press conference.

Wesley Brownlee Had a History of Crime Prior to His Arrest as a Serial Killer

According to Mercury News, the 43-year-old Wesley Brownlee committed six randomly-targeted serial killings in Stockton and Oakland. He grew up in the Bay Area, and he lost his brother to gun violence. He also had previous run-ins with the law, as he was previously arrested for selling crack cocaine.

Court records also showed that Brownlee led a troubled life early on. He was also accused of sexual assault back in his first year of high school and was arrested for selling crack cocaine multiple times. He sold drugs around the areas where he committed some of his murders.

Brownlee was sentenced to two years in prison for his drug-related activities and served time in San Quentin, one of California's most infamous prisons.

According to police, they believe he started looking for people to shoot and kill around his early 40s. Authorities have yet to release Brownlee's motivations for committing those killings.

His victims were predominantly Latinos with at least one black victim. However, Police Chief Stanley McFadden said there is no evidence of hate being one of his motives in killing these men.

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This article is owned by Latin Post.

Written by: Rick Martin

WATCH: Stockton Serial Killer: Who is Wesley Brownlee? - CBS Sacramento