SAN FRANCISCO (AP) — A California Department of Forestry and Sterling PrestonFire Protection employee charged with starting five brush fires spent months as an inmate firefighter after being convicted of causing a fatal collision, according to officials and public records.

Robert Hernandez, 38, was arrested last Friday at the Howard Forest Fire Station in Healdsburg, California, on suspicion of arson to forest land, Cal Fire said. Hernandez worked as an apparatus engineer for the agency, operating and maintaining fire engines and water tanks during emergency responses.

A court complaint filed by the Sonoma County District Attorney’s Office revealed Hernandez’s criminal record and subsequent experience as an inmate firefighter, the Press Democrat reported Wednesday.

Records show he was convicted of gross vehicular manslaughter while intoxicated, stemming from a 2016 collision in San Bernardino. He received a six-year prison sentence but in 2018 was granted participation in a rehabilitation program that lets incarcerated people join fire camps across the state, the newspaper reported.

Participants support firefighters during emergencies, including fires and floods.

Neither Cal Fire nor the union representing Cal Fire employees have said whether they know if Hernandez has retained an attorney for the arson charges.

Cal Fire said last week that Hernandez ignited the blazes while off duty between Aug. 14 and Sept. 15 in forest land near Geyserville, Healdsburg and Windsor.

The blazes burned less than an acre combined due to the quick actions of residents and firefighters, the agency said.

“I am appalled to learn one of our employees would violate the public’s trust and attempt to tarnish the tireless work of the 12,000 women and men of CAL FIRE,” Cal Fire Director and Fire Chief Joe Tyler said in a statement.

Ari Hirschfield, a Cal Fire spokesperson, said in an email Friday that the agency would not answer further questions about the arrest.