BARNSTABLE, MASS. (WHDH) - The man accused of killing Yarmouth Police Sgt. Sean Gannon in 2018 acted in self-defense, his attorney said Friday as jurors heard opening statements and initial testimony in the murder trial of Thomas Latanowich.
Latanowich, of Somerville, faces a first-degree murder charge in Barnstable Superior Court in the death of Gannon.
Gannon, 32, the department’s K-9 officer, was killed in April 2018 while he and other officers were serving an arrest warrant for a possible probation violation at a Barnstable home. Gannon’s dog, Nero, was also shot, but survived.
Latanowich, described by prosecutors as a career criminal with a lengthy record, is also facing other charges, including assault and battery with a dangerous weapon, firearm possession without a license, and mistreating/interfering with a police dog.
Prosecutors say Latanowich was hiding in the attic and that officers warned him that they were coming in, making multiple announcements. But under cross examination, a Barnstable police shift commander who responded to the scene was grilled about why he never documented those details in a police report.
When questioned by defense attorney Joseph Krowski, the shift commander testified that he failed to document the detail about officers announcing their presence at the home and admitted that it was an important piece of information to leave out of the reports.
Krowski also told the court that his client acted in self-defense and was afraid for his life because the officers were the aggressors. The lawyer added that his client never planned or expressed desire to harm Gannon.
Prosecutors stated that evidence presented during the trial will prove that Latanowich is guilty of committing the murder with deliberate premeditation.
Latanowich has pleaded not guilty and has been held without bail since his arrest.
The trial is expected to last up to four weeks and as many as 60 witnesses could take the stand before the jury gets the case.
The trial will resume Monday and is expected to last three to four weeks, according to the judge.
(Copyright (c) 2026 Sunbeam Television. The Associated Press contributed to this report. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)