Cops nabbed a crazed stalker who allegedly gunned down his ex-girlfriend in Brooklyn earlier this month before she could get a new restraining order against him, cops said.

Bernsley Barthelemy, 25, was arrested today at 270 Empire Blvd. and charged with murder and criminal possession of a weapon, cops said.

Barthelemy allegedly shot Kazan Raoul, 24, in the face and arm in her basement apartment on Strauss Street in Brownsville around 6:30 a.m. on March 7, cops said.

He was arrested four days before allegedly killing her for violating an order of protection by showing up at her apartment and peeking through a window. At his court appearance for that incident on March 5, he posted a $7,500 bail.

He also violated a restraining order three times last fall and was arrested in December and February. He pleaded guilty to criminal trespassing and aggravated harassment.