Former acting Lucchese mob boss Matthew Madonna ordered a 2013 Bronx hit on a onetime ally after the man refused to repay a $100,000 loan, a prosecutor said Monday.

The statement came during opening arguments in the White Plains trial of Steven Crea Sr., Christopher Londonio, Terrence Caldwell and Madonna — who are accused of racketeering conspiracy and other charges for their respective roles in the Lucchese organized crime family.

Prosecutor Celia Cohen told jurors that Madonna and Crea ordered the murder of notorious Purple Gang leader Michael Meldish after Meldish told Madonna to “f–k off” when he asked about his money.

“Not repaying a boss is a dangerous game,” said Cohen, adding that Londonio and alleged triggerman Caldwell subsequently executed Meldish as he sat in his parked car in November 2013.

“Michael Meldish is dead because of these four men,” said Cohen.

In addition to racketeering, the reputed wiseguys are also accused of extortion, loansharking, illegal gambling and other acts of ruthless violence. Londonio is also facing a separate charge for stockpiling bed sheets while in custody — purportedly as part of a plot to escape out the window of a federal lockup.

Lawyers for the four men encouraged jurors to focus on the array of turncoat cooperators expected to take the stand during the trial.

“They have lied, stolen, cheated — they put their own personal interests above all else,” Crea’s lawyer Robert Franklin said of the government cooperators.

Caldwell’s lawyer George Goltzer also emphatically denied that his client killed Meldish — noting the two were such close friends that Meldish routinely drove Caldwell to the hospital for chemotherapy.

Later Monday, jurors heard testimony from a mother and daughter who discovered Meldish’s remains.

“We saw a car door and someone’s leg hanging out of the car,” retired nurse Janet Forbes testified. She drove the car around the block, and pulled up alongside to investigate, thinking he might be in a booze-induced stupor.

“When I saw him up close he didn’t look drunk, he looked dead,” said Forbes.

Madonna, 83, served as the Lucchese family’s “street boss” until 2017, when the formal boss Vittorio “Vic” Amuso — who’s serving out a life sentence for murder — allegedly appointed Michael DeSantis in his stead.

The trial continues Tuesday.