The MTA bus driver charged with mowing down an elderly woman in Brooklyn has a record of busts for drug possession and assault, law-enforcement sources said Wednesday.

Paul Roper has three sealed arrests, two of which are separate cases in 2007 for drug possession and felony assault, the sources said. He also has a 2012 collar for misdemeanor assault, they said.

The hefty MTA man was arraigned in Brooklyn Criminal Court on Wednesday on charges that include leaving the scene of the accident after allegedly running over Carol Bell, 70, as she crossed a street Tuesday.

Roper, who has worked for the MTA for 15 years, was making a left turn in his B15 bus at Fulton and Sackman streets when he hit Bell, trapping her under the vehicle’s rear wheels and mangling her body.

The entire incident was caught on surveillance video and shows Roper briefly stopping the empty bus — then continuing on his route.

Warning: This video may be disturbing to some viewers

“The sound made by the impact was heard by several civilians,” said prosecutor Wilfredo Cotto. “The pedestrian was dismembered.”

Defense attorney Clifford Levin argued at the arraignment that Roper couldn’t see Bell because of a blind spot located on the left side of the bus.

“I’ve already confirmed this particular model of bus that he was driving has had litigation because of a blind spot on the left-hand pillar,” Levin said.

Under a lawsuit settlement in September, any driver cannot be arrested solely for hitting a pedestrian in a crosswalk. A finding of negligence is required first.

Levin also told the court that Roper has “never had a criminal conviction of any type.”

An MTA spokesman said the agency was aware of Roper’s three previous run-ins, which he’s required under contract to report, but added that none of them warranted termination.

The sources said Roper has never failed a drug or alcohol screening, which are given to MTA employees at random.

The judge suspended Roper’s driver’s license and set bail at $25,000 bond over $25,000 cash.

His crying wife, Sonia, declined to comment on whether the family could make bail.

Terry Collins, 30, Roper’s son, said, “My pops has been on that job for 15 years. He probably didn’t see her.”

Additional reporting by Ben Feuerherd