Two men who tricked hundreds of homeowners and municipal customers into paying them for fraudulent engineering services were convicted Wednesday on charges including forgery, identity theft and grand theft.

The pair, who once worked for a engineering firm in Rolling Hills Estates, provided fraudulent work on more than 700 commercial and residential properties across at least 50 cities in Southern California, according to estimates from investigators.

Los Angeles Superior Court Judge Lisa B. Lench heard the case against Wilfrido Rodriguez, 47, and Ruben Gutierrez, 45, who waived their right to a jury trial.

Rodriguez—who worked as an engineering drafter—was convicted of more than 250 counts and acquitted of 129 other charges, while Gutierrez—who worked as an architectural designer—was found guilty of 205 counts and acquitted of 46 others.

The two forged the signature of one of the licensed civil engineers that owned Palos Verdes Engineering in Rolling Hills Estates, where the two had worked, and used the victim’s engineering seal to deceive homeowners and municipalities into believing that the victim had personally drafted engineering plans and conducted structural observations as structures were being built, said Deputy District Attorney Jeffrey Stodel.

The fraud was not discovered until March 2014 and reported to the Los Angeles County Sheriff’s Department soon afterward, the prosecutor said.

Rodriguez and Gutierrez were criminally charged last year.

Rodriguez could face a potential sentence of more than 170 years behind bars, while Gutierrez could face a maximum of 141 years in custody, according to the district attorney’s office.

Gutierrez’s attorney, Bill Seki, said he plans to ask the judge to sentence his client to probation.

“It’s an incredibly complicated case and I think the judge put a lot of thought into it,” Seki said outside court. “Despite her ruling, we believe there are legal issues we would like to address in an appeal.”

Seki had said last year that there were no allegations of any defects as a result of the engineering plans involved in the case.

The two men remain free on bond while awaiting sentencing Jan. 27 at the downtown Los Angeles courthouse.