A 38-year-old convicted sex offender living in Apple Valley was arrested again last month after investigators determined he was frequenting schools and manufacturing illegal firearms, authorities said Tuesday.

Tier-three sex registrant Brian Bolik was under investigation for suspected violations between April 2 and June 27, the San Bernardino County Sheriff’s Department stated in a news release.

“During the investigation, detectives served search warrants in Apple Valley and Hesperia. Illegal firearms, including an AR-10, an AR-15, and two semi-automatic handguns were seized,” the Sheriff’s Department stated.

Authorities also determined Bolik was in violation of his sex registrant terms, saying he went to schools in San Bernardino and Los Angeles counties to look for work.

Bolik, who is required to register as a sex offender for life, was arrested and booked on June 24 on suspicion of being a felon in possession of a firearm, manufacturing an assault weapon, felon in possession of ammunition and violating sex registrant terms.

Tier 3 is reserved for the highest-risk offenders, including “individuals convicted of the most serious sexual offenses, often involving violent sex crimes or crimes against children,” according to a Los Angeles criminal lawyer website.

Bolik remains in custody without bail, the Sheriff’s Department stated.