MARTINEZ — An alleged con artist with a lengthy rap sheet is back in police custody, ending a search that spanned for months, during which time he allegedly continued to bilk elderly couples out of money.

Adan C. Rivas, 41, of Modesto, is in jail on a $600,000 warrant, prosecutors announced Thursday. He faces a total of 38 criminal charges for alleged offenses dating back to 2020. They include financial elder abuse, theft by false pretense, theft with specified priors, and violations related to his fraudulent contracting practices, court records show.

Authorities allege that Rivas — who in 2018 was sentenced to 76 months in state prison in a similar case — made a living by posing as an honest businessman. They say he would target affluent communities, offering gardening and tree trimming services under business names like New View Tree Care, Gutierrez Tree Services, and while using the pseudonym Adam Rivas. But then he’d allegedly take the money and disappear, leaving the projects unfinished or partially completely.

Rivas was initially charged with seven crimes in March 2022, with offense dates covering the two previous years. But according to police, that didn’t stop Rivas from continuing to scam older residents. Last May, a Concord couple in their late 70s told police they paid Rivas $10,000 for tree trimming, to install a drought-resistant garden, and other upgrades. They claimed he completed only a “fraction” of the agreed upon services then stopped returning their calls, according to court records.

A 78-year-old Contra Costa resident told authorities she lost $800 to Rivas for unfinished tree trimming, and another couple alleged they lost several thousand dollars when Rivas failed to complete upgrades that would make it easier for their daughter, who suffers from a physical disability.

Rivas was charged in August with dozens of new criminal offenses, with the March case still active. Police had been trying to locate him ever since, and nothing — including attempting to track his phone — worked. He failed to show up at an October court date, prompting a judge to add another $75,000 to his arrest warrant, which at that point topped $500,000.

Rivas was back to his old tricks, authorities said. In December 2016, he was listed as a subject on the Contractors State License Board’s “Most Wanted Wednesday” feature for an active warrant involving similar allegations and a dozen Bay Area victims.

Rivas’ criminal history includes misdemeanor convictions for grand theft, felony convictions for multiple counts of financial elder abuse and one count of unlawful sexual intercourse with a minor, according to police.

Jail records indicate that Rivas was transferred to Contra Costa from federal custody, but the exact circumstances of his arrest were not available at press time. The jail intake form lists his profession as “gardener.”