A Maryland man described as a “career thief” by prosecutors was sentenced to 12 years in prison Wednesday for stealing more than $25,000 in valuables from cars in the Potomac area of Montgomery County.

Michael B. Dorsey, 47, of Silver Spring was found guilty in five separate trials last month of 20 counts that included felony theft, identity theft and misuse of a credit card. Dorsey targeted parking lots near restaurants and other attractions in Potomac, stealing wallets, cellphones, laptops and other items from parked cars between March and October 2011, according to police documents.

One of his victims was Deborah Beers, the mayor of Glen Echo.

When police searched his home, they found dozens of items he had been seen wearing in surveillance videos or had stolen from cars, authorities said.

“When a defendant preys upon our citizens while they enjoy recreational facilities of our county like the golf courses, tennis courts and pathways of the C&O Canal, we have to hold them accountable,” said Ramon Korionoff, a spokesman for Montgomery County State’s Attorney John McCarthy.

Dorsey’s sentencing Wednesday stemmed from four of his convictions; he faces another sentencing Thursday in the fifth trial. That sentencing was also scheduled for Wednesday but was postponed when Dorsey, who is representing himself, complained that he had been given too little notice to prepare after the date was changed.

“I feel like I’ve been bamboozled,” Dorsey told Montgomery Circuit Court Judge David A. Boynton. At times appearing confused by the intricacies of the legal system, Dorsey claimed that the public defender assigned to him had failed to fulfill his basic duties — and dismissed him at the start of his hearing.

It was the third time Dorsey had dismissed his public defender. Dorsey represented himself at all five trials.

Dorsey’s father said the evidence brought against his son during the trials, including the video surveillance footage, was unconvincing.

“The prosecutor said, ‘It looks like him.’ Well, I look like him,” Michael B. Dorsey Sr. said shortly after his son had been taken away in handcuffs, clasping a folder full of documents behind his back.

Dorsey was previously convicted of house breaking, forgery, grand larceny and credit-card fraud, among other crimes, said Assistant State’s Attorney Stephen Chaikin.

Chaikin said he would ask for an additional 41 / 2 years at Thursday’s sentencing.