Investigators believe David W. Park walked through an unlocked rear door when he entered an Amherst home where the resident shot and killed him, sources close to the case told The Buffalo News.

The rear door led from a raised deck into the home on Millbrook Court where Park was shot as an intruder early Sunday.

Police who responded to the home soon after the shooting found no indication of a forced entry.

Park was not shot immediately after entering the home, said Thomas H. Burton, attorney for David D'Amico, the homeowner who shot Park.

"The rear door where he entered was on the other side of the house from the location where he was shot," Burton said. "[Park] walked through the kitchen and two other rooms before ending up at the location where he was shot."

Police believe Park entered the D'Amico's backyard by opening a gate, which he closed behind him, sources said. He then went up onto the deck and stepped inside the home.

The question of whether the door was locked had been a tightly guarded secret until Wednesday, when three sources familiar with the case confirmed for The News that it had been left unlocked.

D'Amico routinely locked all of his doors at night and has told Amherst police that he was unaware that his rear door had been left unlocked that night, the sources said.

Amherst police and the Erie County district attorney's office are investigating the death of Park, 31, an award-winning Albany school teacher who was in town to attend a party at a home next door to D'Amico's.

So far, no charges have been filed against D'Amico. His attorney hopes no charges ever will be filed.

"Whether a door was locked or not is not an issue under the law," Burton said. "An unlocked door does not give someone a defense to commit a burglary. The narrow focus of the law is on what was in the mind of the man who fired the shot.

"No matter how [Park] got in, I can tell you this much for certain — he was not invited in. He was an intruder."

A memorial service for Park will be held today in his hometown of Old Forge. A second memorial service will be held Friday in Albany, where he was a beloved elementary school teacher.

Assistant Police Chief Timothy M. Green, spokesman for the Amherst police, declined to confirm or deny The News's information on the unlocked door.

"As we've said since this happened, this was a tragedy," Green said. "I don't know why [Park] was in that house, but he should not have been. We haven't found any evidence indicating that he was legally in the house."

D'Amico fired his hunting shotgun because Park did not comply with his demand that he leave the house and because he feared that Park was about to walk upstairs to where the D'Amicos had been sleeping, Burton said.

Park is believed to have gone into D'Amico's house by mistake after leaving the party next door. "The reason why he went into [D'Amico's] house is a mystery we may never know the answer to," Green said.

The Erie County medical examiner's office is conducting toxicology tests to determine if Park was intoxicated at the time.

Both D'Amico and his wife, Julie, have been "emotionally devastated" by what happened, according to Burton.

"There are winners and losers in life," Green said. "But any way you look at this case, the outcome is bad for everyone involved." Millbrook Court, Amherst