A suspect was arrested and charged Saturday in connection with the fatal stabbing of a 14-year-old boy in the South Bronx Friday morning, police say.

Waldo Mejia, 28, has four prior arrests, the most recent being in November for stabbing a doorbell camera, according to the NYPD.

At a news briefing Saturday, NYPD Commissioner Jessica Tisch said the attack was random, and not related to any gang activity.

"When he was arrested, Mr. Mejia was wearing the same sneakers and pants he wore during the homicide and he was in possession of a bloody knife. Mr. Mejia, a violent recidivist with a documented history of mental health interactions with the NYPD, is now at the 40th Precinct being processed on a murder charge," Tisch said.

The stabbing happened Friday morning near NYCHA’s Mitchel Houses on East 138th Street by Third Avenue in Mott Haven, the NYPD said.

Police say the boy, identified by Bronx Borough President Vanessa Gibson as Caleb Rios, was standing by himself when Mejia allegedly went up to him and stabbed him twice in an unprovoked attack.

Gibson says Rios was on his way to school.

Mejia is being charged with second-degree murder, first-degree manslaughter and fourth-degree criminal possession of a weapon, according to police.

Mejia is also connected to another unprovoked stabbing on the same block, police say.

That attack happened last Sunday on the staircase of the Third Avenue-138th Street subway station, the NYPD said.

Police say a man was approached and stabbed once in the left arm, but is expected to recover.

Attorney information for Mejia wasn’t immediately available Saturday.