Prosecutors say Timothy Kostka broke into Barbara Coyne’s residence in South Boston on Patriots Day last week looking to steal high-end fishing equipment, but encountered the 67-year-old grandmother during the break-in and fatally stabbed her.
“The defendant . . . slipped into Barbara Coyne’s home in broad daylight, beat her, and slashed her throat, leaving her bloody and dying,’’ Ursula Knight, assistant Suffolk district attorney, said during Kostka’s arraignment Monday in South Boston District Court.
At 9:30 a.m., on April 16, 30 minutes before Barbara Coyne was stabbed, Kostka, 26, of South Boston, allegedly called a contact asking where he could sell some high-end fishing equipment. “He then set out for 737 East Seventh Street, where he expected Richard Coyne’s equipment to be but not Richard Coyne.’’ Richard Coyne is Barbara’s son.
Authorities would not detail the specifics of the fishing equipment.
Richard Coyne, an avid jogger, had planned to run in the Boston Marathon but decided not to because of the high temperatures. He saw his mother in her kitchen at the residence only minutes before the attack, Knight said. At about 10 a.m. he went to check on her.
With her last words, Barbara Coyne described the knife-wielding assailant to her son, a description that, according to Knight, matched Kostka, who stands 6-feet-3 and weighs about 280 pounds.
Thirty minutes after the break-in, Barbara Coyne was pronounced dead at Massachusetts General Hospital.
Authorities said that minutes after Coyne’s son called 911, surveillance video showed Kostka at a variety store not far from Coyne’s address.
Kostka allegedly placed a call to buy heroin and then changed his clothes. He switched clothing again in the afternoon, at about 1:30 p.m. near O Street, authorities said. Police recovered clothing and a butcher knife at that location and are testing the items for evidence.
Prosecutors believe Kostka arrived at Coyne’s house carrying a knife.
Police combed through Coyne’s first-floor residence, looking for evidence, and found fingerprints on two jewelry boxes, a coin jar, and furniture. Knight said the fingerprints matched Kostka’s and that authorities also have surveillance video and other evidence linking Kostka, an unemployed electrical apprentice, to the crime.
Kostka appeared in court Monday wearing a dark gray sweatshirt. With his hands cuffed in front of his body, he focused mostly on Judge Michael Bolden during the 20-minute arraignment. On two occasions, Kostka whispered to his attorney, William E. Gens.
Gens, who pleaded not guilty on Kostka’s behalf, said the defendant’s family and the victim’s family have known each other for at least 20 years, and for that reason the fingerprints should not be considered incriminating evidence.
“Standing alone, fingerprints are weak evidence, especially since there’s no way to date them, when you have people who know one another,’’ Gens said after the arraignment.
About 20 family members and friends of Barbara Coyne attended the arraignment, some crying softly as Knight gave details of the homicide. At the other side of the courtroom sat Kostka’s family and friends. A woman in the group identified herself as the aunt of the defendant, but would not comment further.
Members of Kostka’s family, who were gathered at the family home in South Boston, also did not want to comment Monday night. A man answering the door at Richard Coyne’s home declined to speak to a reporter.
Authorities said Kostka’s name surfaced as a person of interest in the “immediate aftermath of the crime.’’
Kostka had been arrested Friday on an unrelated matter, a break-in last November, and was arraigned on that charge Monday. On the homicide charge, he was ordered held without bail, and was also ordered held on $250,000 cash bail in the break-in. Kostka is scheduled to return to court on May 24 for a probable-cause hearing.
Late last year the defendant allegedly revealed to an acquaintance that he was doing break-ins in the area of E Street at times when residents would be asleep, Knight said.
“When asked what he would do if someone woke up, the defendant replied that he would slash their throats,’’ Knight said.
Brian Ballou can be reached at email@example.com.