The homeless man accused of shoving a woman onto the subway tracks in Downtown Manhattan across the street from City Hall had zeroed in on his victim and trailed her until he could pounce, prosecutors said Saturday.

Samuel Junker, 41, was caught on camera following victim 34-year-old Xu Yanan from the turnstiles at the Chambers St. station down to the 1/2/3 platform about 11 p.m. Tuesday moments before he shoved her onto the railbed below, according to court documents.

“His only aim when he entered the subway station was to push the victim onto the tracks, and then escape immediately,” Manhattan Assistant District Attorney Madeline Holbrook explained at Junker’s arraignment, where the alleged subway shover was ordered held on $250,000 bail.

Yanan broke her leg in the fall. Other straphangers helped her get back on the platform before a train came into the station.

Junker, whose last address was a White Plains homeless shelter, was arrested in TriBeca Thursday after he was caught acting eratticly on Broadway near Lispenard St.

Junker was taken to Bellevue Hospital for an evaluation, but cops immediately recognized him as the man sought for the Tuesday shoving. The suspect was still wearing the ratty red shirt, jeans and work boots without laces that he was wearing at the time of the attack, prosecutors said.

Holbrook said investigators were trying to determine if the evidence “supports higher charges” including hate crime charges.

Station surveillance cameras recorded Junker going in and out of the station, prosecutors said.

“(He) proceeded to travel down the stairs, speeding up, in order to follow (his victim),” the criminal complaint against Junker notes.

Before the shoving, Junker was arrested twice in White Plains over the summer for criminal mischief and trespass.

He was arrested for trespass on Aug. 20, about a week before he shoved Yanan onto the tracks, prosecutors said.

He has no convictions in New York, but has several in Georgia, where he was repeatedly arrested for criminal mischief and “exposure of sexual organs,” proseuctors said.