The three children and a sister of Lynne Brennan, 53, pleaded Monday for the public’s help to solve her murder in Manchester that will soon mark its 15-year anniversary.

For the first time, prosecutors confirmed that Brennan died due to blunt-force trauma. Police came to her apartment at 267 North River Road on Oct. 11, 2010, to find her dead, but they believe the crime happened at least a day earlier.

They also released a never-seen video clip of a tired-looking Brennan, shopping at the nearby Bunnie’s Superette at 3:29 p.m. on Oct. 4, the last time she was seen in public, said Christopher Knowles, head of the state’s Cold Case Unit.

At the time, she was wearing a white long-sleeved sweater, black stretch pants, light-colored shoes and was carrying a large black purse.

Jason Brennan,

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