Stephen Moore was lounging in his second-floor bedroom one Saturday afternoon last month, channel-surfing with his shoes off, when, he says, he heard his home security alarm blare: "Front Door Open."

Downstairs, police officer Larry Shields entered the vestibule.

In October, Shields had been cleared of criminal charges by the District Attorney's Office and the Police Department's Internal Affairs Division for shooting an East Frankford man in his home in front of his fiancee and children. Now, Shields was about to fall under investigation for shooting someone else.

Moore, 37, of West Philadelphia, a seasonal water-ice vendor and part-time electrician, was not armed. He was not being sought for a crime and had not called police.

Shields, a four-year veteran assigned to the 18th District, was the first officer to respond Nov. 9 to 6019 Christian St. for a report of a "burglary in progress." It was warm. Neighbors were out. Children played.

The 911 complaint, investigators would learn, was made by a parent of Moore's late wife, Halimah Ramadan, who died in August of cancer. Moore and his wife bought the redbrick house and moved in in February 2010. The estate is in Ramadan's name and is not settled. Moore's in-laws want him to move out.

The in-laws were not at the property when they called police twice that Saturday, claiming that someone was in the house who did not live there.

Moore went downstairs to check the alarm.

Shields, according to law enforcement sources, told investigators he found the front door slightly open and went inside, where Moore advanced toward him in the living room and made a threatening movement toward his waist. Shields said he backed up and fired from the porch.

Moore said he made no threatening movements and had no time to approach Shields. Shields did not identify himself and fired without warning from behind the cracked-open vestibule door, Moore said.

"No words were exchanged," Moore said recently in his University of Pennsylvania Hospital room. "I didn't say anything. I just came down the steps and saw someone in the doorway, and the guy just shot me, just that fast."

The slug left two holes the size of silver dollars in Moore's right arm, then ripped into his chest, collapsing a lung. Four operations later, he has been released from the hospital.

Shields, in his late 30s, has been placed on desk duty and cannot comment on the case because it is an open investigation, said Lt. Ray Evers, a Police Department spokesman.

In April, Shields shot Josh Taylor, 23, in Taylor's home after a confrontation on the street.

Shields was helping his sister move into a house in the 4600 block of Worth Street when he noticed Taylor walking to a neighbor's with a Glock handgun in his waistband, police said.

"Hey, my man, come here. Police," Shields said, according to Shields' nephew's statement to investigators.

According to the District Attorney's Office, Taylor ran into his home with Shields in pursuit. Once inside, they said, Taylor pointed his gun at Shields, who fired once, striking Taylor in the chest.

Taylor, a union roofer, recovered from his wounds and is in prison, facing attempted-murder charges. In October, Taylor filed a civil suit against Shields and the City of Philadelphia.

According to the suit, Taylor was showing a neighbor a newly bought handgun when Shields confronted him. Taylor told Shields that it was a licensed gun and that he was going back in his house, the suit claims. Shields chased him inside and fired after Taylor stumbled to the floor, with his gun a safe distance away, according to the suit

Craig Straw, the city solicitor representing Shields, could not be reached for comment.

Tasha Jamerson, a spokeswoman for the District Attorney's Office, said the Moore shooting would not affect the prosecution of Taylor.

Shields was returned to full duty in June after an Internal Affairs review found he broke no department rules - about four months before the District Attorney's Office cleared him of criminal charges.

That's department policy, Evers said, since the procedural reviews of police shooting investigations can stretch for years.

"If they don't see any apparent department violations or any issues criminally, they will put you back on the job," he said. "That shooting was investigated as thoroughly as any police-involved shooting, as will this one."

Shields' earlier shooting will not influence the current investigation, Evers said.

"I don't think you can subject him to that, because he was cleared. It's a clean sheet of paper," Evers said.

Shields has worked in Philadelphia law enforcement for 18 years. From 1993 to 2007, he was a guard in the Philadelphia prison system, said Shawn Hawes, a prison spokeswoman. The prison department does not comment on employee work history, she said.

Shields has had two previous complaints filed against him, said Lt. Kevin Long of Internal Affairs, one when his partner was accused of pushing a man down steps during a domestic-dispute call, another when someone claimed Shields issued an improper traffic citation.

Shields was exonerated in both cases, Long said.

In his hospital bed, Moore caught his breath and coughed. Machines connected to tubes connected to his chest made beeping sounds. He showed photos of rows of staples running down his side and across his chest.

"I'm a walking autopsy," he said.

He had just come in the house after talking with some neighbors, he said of last month's shooting.

His alarm sounds an alert whenever the door is opened, he said.

Hearing the alarm, Moore walked down the steps to the first-floor landing. He noticed the vestibule door was cracked open.

"I see someone is there, and then I see his hands like this," Moore said, making his hands like a raised gun. "I'm trying to make sense of who this person is, and the next thing I know, bam, he shot me."

He said he did not remember the flash of the gun, just the sound. "It knocked me down, I'm on the floor, and I see I'm bleeding, and I'm thinking this guy is going to kill me."

He said he tried to crawl toward the front door: "I was thinking, 'I don't want to die in this house.' "

Shields backed out toward the porch, yelling, "Who's behind the door?" Moore said.

"I said, "Nobody. I live here."

Other officers arrived, quickly searching the house, finding Moore's passport and utility bills. Neighbors said they heard Moore yelling shortly after the shooting. "I remember him screaming at the top of his lungs, 'It's my home. I live here!' " said one neighbor who asked not to be identified but who called Moore a "pleasant man."

Police carried Moore by his arms, legs, and belt into the back of a patrol car. "They carried him like he was on a spit," the neighbor said.

On the ride to the hospital, Moore, a Muslim, was losing consciousness.

"I thought I was dying. I was saying my different prayers," he said.

He woke up the next morning in the emergency room. His attorney told him about Shields' previous shooting. Moore's attorney, Craig Sokolow, said he would file a civil lawsuit against Shields and the city as early as this week. Moore said he respects the police. He said his shooting is a training issue.

"From the police I know, I wouldn't expect someone to perform like this," he said.

"I mean, who gets shot in their own house?" "That's not supposed to happen."

Contact staff writer Mike Newall at 215-854-2759 or mnewall@phillynews.com. Follow him on Twitter @MikeNewall.