A Halethorpe man under indictment on weapons charges blasted his way into a Hampstead home with a shotgun Tuesday morning and killed his ex-wife's fiance and then himself, police said.

Michael Leo Swift III, 45, pulled into the driveway in the 1200 block of Allview Drive, left the engine running in his dark-green Saturn and burst through a sliding-glass door in the back of the house with the 12-gauge shotgun. Police found Zaidan Stephen Asid, 51, dead in a first-floor family room, said Maryland State Police spokesman Greg Shipley.

Swift's body lay nearby, the weapon still in his hands, Shipley said.

Hallie Patricia Swift, 44, called police from the house about 11 a.m., saying her ex-husband had just broken in, shot her fiance and then himself. She was not injured but was taken to Carroll Hospital Center.

Police could not say what might have provoked the attack.

"It's just unbelievable," said neighbor Jane Snyder. "The poor man has had enough heartache."

Last New Year's Eve, Asid's only child, Noah, died after he was struck by a falling hickory tree at a nature camp at Hashawha Environmental Center in Westminster. The 9-year-old boy "was the love of his life," Snyder said.

Asid, known to neighbors and co-workers as Steve, had moved with the boy's mother into the neighborhood about six years ago. The couple were divorced a short time later.

A computer engineer who worked for a software development firm in Columbia, Asid was engaged to Hallie Swift, co-worker Susan Boyer said. The two were planning to be married in Cancun, Mexico, in September.

Because of the distance to his office at Credit Management Solutions Inc., Asid worked from home two days a week, said Boyer. At work, he was one of a core group that ate lunch together regularly.

"Everyone at work liked Steve," said Boyer, who called him "positive and generous," a person who would stay up all night if necessary to solve a problem for an employee or a customer. "When you read a story like this in the paper, you're tempted to think there must be something tawdry with the person involved," Boyer said. "That couldn't be further from the truth. Steve was a terrific guy."

Boyer said Asid was expected at the office Tuesday but had stayed home to help Hallie Swift with an unspecified personal problem. Boyer answered the phone at CMSI when Asid's mother, Shirley, called with the news.

"Her voice was breaking. She was teary. She said something had happened at the house, and the pit of my stomach went out," Boyer said.

Asid and Hallie Swift shared enthusiasms for rock music, cooking and traveling. He loved North Carolina-style barbecue, and when Boyer asked him for a restaurant recommendation recently, he mentioned a place in Hampstead that was known for its hush puppies.

Neighbors described Asid as helpful, friendly and devoted to his son. Snyder, her husband, Tom, and their daughter, Shelley Ordway, talked about seeing him often outside the two-story yellow house flying a kite or playing ball with the boy.

"Steve was always a caring and involved father," said Ruth Loveless, an owner of Shiloh Stepping Stones Child Care Center in Hampstead, where Noah was enrolled from the age of 2 up through the day he was killed in the freak accident.

"Every kind of event that Noah was involved in, his father helped with in some way or was present," she said. "Noah was a rambunctious little person," and "Dad was the person we'd talk to. He was always very understanding, always expected Noah's behavior to be good."

Court records show that Michael L. Swift was arrested by Baltimore County police in January on weapons charges, including possessing unregistered machine guns, possessing unregistered rifles, possessing destructive devices and obliterating serial numbers on weapons.

Baltimore County Circuit Judge Susan Souder set bail at $250,000, placed him on home detention and ordered that he was not to have guns, explosive devices or other weapons. On March 1, he was indicted on eight counts of having machine guns, destructive devices and unregistered shotguns.

Court records show that a few years ago, Swift and another woman filed charges against each other including malicious destruction of property, domestic violence and custody complaints.

Baltimore Sun staff writer Justin Fenton contributed to this article.