Darrell Fuller entered a Queens preschool and paced "back and forth" while using a cellphone, a witness at his murder trial said Wednesday.

At the time, a manhunt was underway for the person who gunned down a Nassau County police officer and a motorist.

"I asked him, 'Can I help you?' " said Claudette Knight, a teacher at the St. Albans school.

Knight testified that Fuller told her he was there to see his godson. She said Fuller greeted the little boy, then stepped away to look through a glass door.

"He was just on his phone and pacing back and forth," Knight recalled. The teacher said she saw police cars on the street and could hear a helicopter overhead that day.

Wednesday, jurors watched security videos from the school depicting a man Knight identified as Fuller.

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Prosecutors say Fuller, 34, of St. Albans, hid out in the school soon after slaying Officer Arthur Lopez and Raymond Facey, 58, a construction worker from Brooklyn.

Authorities have alleged that on Oct. 23, 2012, Fuller fled an accident scene and killed Lopez after the officer approached him with a Taser at a traffic stop at the Nassau-Queens border at 241st Street and Jamaica Avenue.

Fuller then drove his disabled car south on the Cross Island Parkway before shooting Facey in the head and fleeing in the man's car, authorities said.

A prosecutor previously told jurors that the first-degree murder defendant tried to make himself look like a victim by having a friend shoot him in an arm and a leg.

Jurors in Nassau County Court in Mineola also heard testimony Wednesday from 911 callers who phoned for help before police found Fuller with gunshot wounds on 111th Avenue in Jamaica, Queens, at about 6:30 p.m. on the day of the slayings.

Retired office worker Mildred Means testified she heard "a pop" from inside a home on the street, before looking out a window and seeing a man on the ground next to a van who was crying out, "Help! Help me!"

Construction worker Radcliffe Murray said he was outside a nearby home when he heard someone say "I got shot," and saw a man crawling out of a red minivan parked behind his truck.

NYPD Officer Michael Boyle testified he arrested Fuller after he found him bleeding at the scene because he recognized his name -- the same as the subject of the manhunt.Fuller faces life without parole if convicted.