The penalty for disabled-parking placard fraud has gone from just a hefty fine to the possibility of state prison time.

The state Department of Motor Vehicles, working with local prosecutors, has begun a major fraud crackdown that led to the weekend arrests of three people in San Francisco - including a mother and son - and the possibility that an additional 26 people around the Bay Area will soon be facing felony charges for allegedly lying on their placard applications.

"This is something we are taking very seriously," DMV spokeswoman Jessica Gonzalez said Monday.

Placard abuse has been breeding resentment, especially in San Francisco, where parking is at a premium - and where there are twice as many disabled placards as there are metered parking spaces.

At least one of the three people arrested over the weekend was ratted out by an anonymous co-worker, authorities say.

Up to 4 years in prison

The three - Guobin Qin, 29, his mother, Qiaoyun Chen, 50, and Yessi Morales, 35, all of San Francisco - have been hit with felony charges and face up to four years in prison if convicted, according to Alex Bastian, a spokesman for District Attorney George Gascón.

The three submitted false documents with the DMV to obtain their parking placards, prosecutors say.

Chen and her son reported that they were being treated by a doctor for a lung disease and filed papers with the doctor's purported signature. However, investigators said the doctor had no record of either being his patient.

Morales said she had arthritis, but neither of the two doctors she identified on DMV applications said they had treated her, prosecutors say.

Morales, who was charged with 24 felony counts, has been freed on $60,000 bail. Qin and Chen, who each face four felony counts, were released after posting $30,000 bail apiece, Bastian said. Charges against the three include fraud, filing false documents, perjury and commercial burglary.

DMV officials say felony charges are expected to be filed against 11 other people throughout the Bay Area, and that an additional 15 cases are under investigation and are likely to result in criminal charges.

The cases are particularly striking in that San Francisco Department of Parking and Traffic officials typically do nothing more than take away a person's placard and issue a $900 citation if they find it's being misused.

However, there has been growing public frustration over an apparent epidemic of placard abuse. There are 29,200 metered parking spaces in San Francisco and 60,700 disabled placards, which allow a person to park all day without charge at any meter or blue curb space.

The difference-maker in the case against the three defendants charged Monday: They allegedly lied to get the placards in the first place.

"The crimes related to submitting a fraudulent application as opposed to catching someone on the street misusing a (disabled parking placard) for parking is quite different," DMV Supervising Investigator Calvin Woo said in a statement.

'Operation Blue Zone'

The DMV says its San Francisco office started an "Operation Blue Zone" investigation in February after the agency received a number of suspicious applications, many of them from people living or working in the city. In some cases, the tip-off was that the applicant's handwriting looked a great deal like that of the "doctor" making the diagnosis, the DMV said.

"The DMV is stepping up disabled placard enforcement in a different, more aggressive way by catching the perpetrators at the beginning stages," said agency Director Jean Shiomoto.

In the entire Bay Area, there are 454,000 disabled placards. And according to Parking and Traffic spokesman Paul Rose, many of the people who hold them visit San Francisco. A 2008 study found that 45 percent of downtown spaces were being used by drivers with disabled placards.

"Our estimates are we are losing more than $20 million a year from unpaid parking as a result of disabled placards," Rose said.