Brandon Kestle was in the bathroom of a Metairie home smoking marijuana and listening to music on his cellphone just before 1:30 a.m. on Memorial Day when he inexplicably decided that he had to kill his girlfriend's mother, Jefferson Parish authorities said this week.

Kestle retrieved a gun from his own room, walked into 66-year-old Linda Paquette's bedroom and shot her once in head in front of her 10-year-old granddaughter, Jefferson Parish Sheriff's Office Detective Harold Wishan testified Tuesday during a probable cause hearing for Kestle, who deputies booked with second-degree murder in connection with the shooting.

"(Kestle) screamed at her to get out of the room, and she left," Wishan said of the child. Kestle then allegedly shot Paquette a second time in the head.

She was pronounced dead at the scene.

Criminal Commissioner Patricia Joyce ruled Tuesday there was probable cause to continue holding Kestle on a charge of second-degree murder.

Wishan's testimony provided new details about the fatal shooting, which occurred at Paquette's home in the 700 block of North Howard Avenue in Metairie.

Kestle had been dating Paquette's daughter for about four years. He moved into the residence a month before the shooting, Wishan said. There was no indication of any trouble or anger between Kestle and Paquette, according to authorities.

After being ordered out of the bedroom, the 10-year-old girl ran crying into the living room where her aunt was sitting on a sofa. It's not clear whether the aunt was Kestle's girlfriend or another relative.

As the girl screamed, "Gun," the woman on the sofa overheard another gunshot from the bedroom, Wishan said.

Kestle then walked out of Paquette's room and out the front door. As he passed through the living room, he told them he would call 911, Wishan testified.

Kestle did dial up authorities and told them to come and pick him up in front of the house. The woman locked the front door as soon as Kestle left the house.

Deputies dispatched to the scene found him outside the residence. He complied with authorities and handed over the alleged murder weapon.

Kestle appeared to be high and "amped up," Wishan testified. "Really just all over the place."

Wishan said Kestle told them what occurred.

In addition to the murder charge, Kestle was booked with being a convicted felon in possession of a firearm. Joyce found there was no probable cause for that charge.

The judge also denied a motion to reduce Kestle's $500,000 bond. He was being held Thursday at the Jefferson Parish Correctional Center in Gretna.