On Monday, a jury convicted Dexter Davis of attempted murder for viciously stabbing his ex-girlfriend with a 14-inch butcher knife.

On Tuesday at 9:35 a.m., he walked out of the Miami-Dade County Jail a free man.

Oops.

Davis’ mistaken release might have gone unnoticed for weeks had it not been for the Opa-locka detective who originally investigated him. Detective Henry Payoute happened to be driving past the Miami jail and noticed a man resembling Davis walking down the street.

Confused, the detective called the Miami-Dade State Attorney’s Office. Minutes later they all realized Davis had been released from jail in error, prosecutors said.

Davis, 36, was still a fugitive Tuesday night as Miami-Dade police mounted a manhunt. A judge issued an arrest warrant on an escape charge.

Davis’ sentencing on the attempted-murder conviction had been set for Dec. 9 in front of Miami-Dade Circuit Judge Daryl Trawick.

A corrections spokeswoman, Janelle Hall, said Tuesday that an internal affairs investigation will determine how jailers accidentally released him from the facility at 1321 NW 13th St.

Tuesday’s incident was another black eye for a corrections department that has long been plagued by embarrassing episodes.

In August, a federal investigation — echoing longstanding complaints — reported that Miami-Dade Corrections was plagued by unsanitary conditions, abusive officers and a lack of proper medical care for inmates.

Another embarrassment came in December 2005, when a serial rapist escaped from the Turner Guilford Knight Correctional Center by shimmying down a rope of bed sheets.

Miami-Dade Corrections Director Tim Ryan noted Tuesday that the department correctly releases tens of thousands of inmates each year with no incident. Still, he said: “Our apologies to the court and to the community.”

Davis was arrested in May 2009 for battering his ex-girlfriend. When he was released from jail, a judge ordered him to stay away from the woman.

But in June 2009 he knocked on her door, demanding to see her. She called police and Davis took off running.

A few hours later, after police had left, Davis returned, bursting into the home and attacking her in front of two children. Miami-Dade prosecutor Anna Quesada told jurors last week that Davis stabbed her about 10 times, leaving the butcher knife jammed in her arm.

She survived with serious wounds, and Opa-locka police arrested Davis outside the apartment.

At trial, Davis took the stand, pleading self-defense. Jurors didn’t believe him, and convicted him Monday after only two hours of deliberations.

Davis’ accidental release may stem from separate notations on his jail card, a record kept for each inmate.

The card notes that Davis was convicted of burglary with assault and attempted murder, with his sentencing court date due in December.

But separately, the card notes, he pleaded guilty to a misdemeanor charge of violating the original “stay-away” order issued by the judge. For that, Judge Trawick sentenced him to 364 days but with credit for all time served — and he had been in jail for more than one year.

“We are looking at how the jail card was interpreted and we are going to give a very serious look during our investigation,” Director Ryan said.