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Norwell Woman Indicted on Charges She Taped Grand Jury, Misled Police Investigation into Marshfield Murder

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Contact:  Beth Stone- (508) 584-8120

BROCKTON – A Norwell woman has been indicted on charges she taped Grand Jury testimony and misled the State Police investigation into the murder of a Marshfield man, Plymouth County District Attorney Timothy J. Cruz has announced.

A Plymouth County Grand Jury today returned indictments against Brianne St. Peter McMahon (DOB: 07/30/79) of Norwell. She was indicted on three counts of Wiretapping, and one count each of Misleading a Police Investigation and Distribution of Transcript or Distribution of Grand Jury Testimony with Intent to Interfere with Criminal Proceedings.

In October, 2015, McMahon traveled with a friend who was also a witness to appear before the Grand Jury convened at Brockton Superior Court. While conducting Grand Jury, State Police assigned to the District Attorney’s Office learned that a phone may have been secreted into the Grand Jury in a witness’ jacket pocket and that phone was used to record the proceedings and interviews.

State Police seized the phone from the witness/friend and later that same afternoon, McMahon came to the District Attorney’s Office in Brockton in an attempt to retrieve the lost phone. She was interviewed by State Police, charged and placed under arrest. Today’s indictments allege that McMahon slipped her Samsung phone into the pocket of her unsuspecting acquaintance and taped the Grand Jury interview of that witness.

On September 16, 2015, the body of 45-year-old Robert McKenna, was discovered dead in his home at 190 Damon’s Point Road in Marshfield. Since that day, State Police and Marshfield Police have worked around the clock to investigate the case and four people have been charged in connection with McKenna’s burglary/murder.

The case was investigated by State Police Detectives assigned to the Plymouth County District Attorney’s Office.


February 3, 2016