The findings could prompt new charges against Nancy Kerrigan's brother, Mark, 45, who has pleaded not guilty to assault and battery on an elderly person and is undergoing a psychiatric evaluation.
Middlesex District Attorney Gerry Leone said Tuesday that an autopsy determined the cause of death was "cardiac dysrhythmia" after a physical altercation with neck compression that damaged Kerrigan's windpipe. The findings also noted that Kerrigan, 70, had high blood pressure and clogged heart arteries.
Several hours later, Kerrigan's family issued a statement through their attorney, Tracey Miner, calling the findings both "premature and inaccurate."
"The Kerrigan family is extremely disappointed that the medical examiner would release a cause of death without having all of the relevant facts," Miner said in the statement.
"The Kerrigan family does not blame anyone for the unfortunate death of Dan Kerrigan, who had a pre-existing heart condition."
The statement did not give details on Kerrigan's heart condition, nor did it elaborate on what facts the medical examiner might not have had. Miner did not immediately return a call seeking comment.
Daniel Kerrigan died Jan. 24 after what authorities said was a struggle with his son.
Police say Mark Kerrigan told them he put his hands around his father's neck and his father fell to the floor after the two argued at their Stoneham home.
Family members had initially said Daniel Kerrigan had a heart attack and his death was unrelated to the argument.
"As a result of these conclusions of the medical examiner, the investigation into Daniel Kerrigan's death, and whether any charges in connection with his death are appropriate, remains ongoing," Leone said in a statement.
The findings imply a strangulation-type injury in a man already vulnerable to heart problems, said an expert not connected with the autopsy, Dr. Ian Paul, associate medical examiner for the state of New Mexico.
"The assault itself would have caused significant physiological stress," Paul said. "It would have put direct stress to the heart itself because the heart is working faster, and in somebody with underlying heart disease, they would be at a much greater risk of experiencing sudden cardiac death."
Cardiac dysrhythmia is loss or interruption of a normal heartbeat, which can lead to cardiac arrest and death.
Denise Moore, an attorney who represented Mark Kerrigan at his arraignment, declined to comment on the autopsy report. Moore said previously that Kerrigan, an Army veteran who had served overseas, was on medication for post-traumatic stress syndrome and was seeing a psychiatrist.
Janice Bassil, Kerrigan's new attorney, did not immediately return a call seeking comment.
Daniel Kerrigan was found unconscious on the floor of his home by police responding to an emergency call at 1:30 a.m. He was taken to a hospital and pronounced dead.
Police said Mark Kerrigan appeared intoxicated when he was found on a couch in the basement of the home. He was "belligerent and combative" but coherent when questioned, police said.
"He stated that he wanted to use the phone and his father would not let him," the arresting officer wrote in a report. "He said he struggled with his father and put his hands around his father's neck and his father fell to the floor."
The officers said they saw blood near where Daniel Kerrigan had been treated by emergency workers and signs of a struggle, including three pictures that had apparently been knocked off a wall and a broken piece of the telephone.
Mark Kerrigan has a lengthy criminal record, with convictions dating to 1991, including drunken driving, assault and battery, domestic assaults, resisting arrest and violation of a restraining order.
In 2008, Kerrigan's parents sued him to recover $105,000 they had spent paying his mortgage at his Wilmington home, taking care of his dogs while he was in jail and paying for a lawyer who represented him on a 2006 assault conviction. A judge dismissed the lawsuit, saying there was no documentation of such an agreement.
He was released from county jail in November after serving time on an assault conviction.
--- AP Medical Writer Marilynn Marchione in Milwaukee contributed to this report.
