MIAMI — When Baron “Dirty” Colon joined an MTV reality show featuring street thugs in 2009, he swore to reform or else wind up behind bars.

His own words may have proved prophetic: Police arrested Colon last week, charging him with the murder of a Miami area artist during a botched heist.

Colon, 24, of Miami Gardens, was a finalist on the second season of MTV’s “From G’s to Gents,” which offered $100,000 to the “real” gangster who most turned his life around. He competed against 15 contestants on the show, which claims to transform “rough-around-the-edges young men” into dapper, successful gentlemen.

He is charged in the January 2006 slaying of artist Marcelo Vera, and according to police was a suspect in the case even as he jetted off to Los Angeles to tape the show.

Investigators got a break last year when a confidential informant secretly recorded Colon confessing to intimate details only the killer would know, according to an arrest warrant filed in court.

Colon is jailed with no bond on charges of first-degree murder and armed burglary. He faces arraignment Jan. 28 in Miami-Dade circuit court.

“From G’s to Gents” is hosted by former P. Diddy assistant Fonzworth Bentley. The executive producer is actor Jamie Foxx.

In his show biography, Colon claims his mother threw him in the trash as a baby, and that she later died of a drug overdose. After stints in juvenile detention and foster care, he became a barber, Colon told the show.

A representative for MTV could not be reached for comment.

Colon’s criminal history shows arrests for drugs, grand theft and driving with a suspended license, but none resulted in felony convictions, court records show.

As a contestant, Colon and company were plunged into the posh world of a Los Angeles “gentleman’s club,” attending a wine-tasting, producing a public service skit for schoolchildren and even competing in a fashion contest.