The ex-con who allegedly slaughtered a wealthy family in their Washington mansion was arrested in DC Thursday night — after a manhunt in New York City.

Daron Dylon Wint, 34, tortured and killed American Iron Works CEO Savvas Savopoulos, 46, his wife, Amy, 47, their 10-year-old son, Philip, and their housekeeper, Veralicia Figueroa, 57, on May 13, police said.

His Brooklyn girlfriend told cops that he had traveled to the city Wednesday night, a week after the carnage, and stayed with her before heading back to DC.

According to local news reports there, he was riding in a panel truck in the northeastern area of the district when it was pulled over. He surrendered without incident and was found with a large amount of cash.

Wint’s brother was also in the truck and was taken into custody along with several other people, Fox 5 DC reported.

Wint was identified after the murders because he allegedly left DNA on the remnants of a Domino’s pizza he ­ordered as he held the family hostage in their $4.5 million home in the Embassy Row area.

Before fleeing, Wint, a Guyana native, set the house ablaze, leaving one of the bodies charred past recognition, police said.

US marshals and the NYPD scoured Brooklyn for the alleged killer after his paramour was questioned Thursday at the 69th Precinct station house in Canarsie and said he had come to town by bus to see her.

However, sources said authorities doubted the credibility of the girlfriend — and weren’t sure he ever made it to the Big Apple.

“We have reason to believe he is not in New York and it’s unclear if he was in New York in the last couple of days,” one source said.

The crime was horrendous.

Three of the victims were beaten and stabbed to death — and young Philip’s body was burned so badly, officials couldn’t tell if he had also been abused.

The Savopouloses were well-known DC socialites and lived a short distance from Vice President Joe Biden’s official residence at the US Naval Observatory.

The Iron Works owner had previously employed Wint, who may have been trying to extort money, according to news reports.

Adding to the mystery, a Savopoulos personal assistant dropped off a package with $40,000 in cash at the home the morning after the family was first taken hostage.

The house burst out in flames a short time later.

The crime wasn’t “random,” according to DC Police Chief Cathy Lanier.

“We do believe that there is a connection between the suspect in this case through the business,” she added.