READING, Pa. — A Pennsylvania state trooper fatally shot a fugitive Arizona sex offender from South Tucson while serving an arrest warrant at a Reading row home.

Police say the trooper opened fire on 35-year-old Richard Carlin around 4 a.m. Friday after he refused to follow police commands.

They say Carlin was on the run since posting bail after allegedly threatening South Tuscon officers with a sawed-off shotgun in 2013.

Carlin was shot in that incident and later sued the city. Records show he's had child molestation and robbery convictions and served time in state prison.

A neighbor who witnessed Friday's episode tells the Reading Eagle he saw police in SWAT gear and heard shouting, an explosion and 5-6 gunshots.

The trooper is a member of the state police's Special Emergency Response Team.

Reading is about 60 miles northwest of Philadelphia.

The South Tucson shooting occurred on Aug. 17, 2013, in an alley in near South Fifth Avenue and East 29th Street. South Tucson Police were called to the area in response to calls of a man with a gun. When Sgt. Sean Masters responded, he said he asked Carlin to stop to answer some questions but he refused, according to documents the Pima County Sheriff's Department provided.

The officer told investigators he saw something beneath Carlin's jacket that appeared to be a firearm, which he said Carlin attempted to reach for.

"Sergeant Masters stated he believed he was going to be shot by the individual and he began to fire his weapon at the individual," the sheriff's report says.

Carlin was hit with several rounds, suffering injuries to his head, abdomen and arm. He was treated at UAMC where he remained for more than a month, according to the civil complaint.

Police found a sawed-off shotgun attached to a sling beneath Carlin's jacket. It was later found to have been stolen in a home invasion.

When sheriff's deputies spoke with Carlin at the hospital, he said he didn't remember what happened the night of the shooting. Hospital staff, however, told the investigators Carlin told them police shot him because he was "waving a sawed-off shotgun in public."

He was released on bond later and absconded.

Here's a link to coverage of the shooting in the Reading Eagle