Department Of Corrections Murder Case Wiped From Records

By DAMIEN FISHER, InDepthNH

The former corrections officer found not guilty of killing Secure Psychiatric Unit patient Jason Rothe at the New Hampshire State Prison for Men now has a clean criminal record.

Matthew Millar, 40, was granted an annulment of his criminal record last month by Merrimack County Superior Court Judge Daniel St. Hilaire. The annulment was granted weeks after a Merrimack County Superior Court jury found him not guilty of Rothe’s 2023 murder.

InDepthNH.org obtained Millar’s annulment application from the public record before it was sealed.

Millar spent more than a year in jail pre-trial after he was arrested in early 2024, and only went home to his family last month following his acquittal. He did not respond to requests for comment.

The annulment means more than the case record no longer being publicly available in court. The court records are sealed, as are any police records associated with the charge. Millar is also now free to tell prospective employers, landlords, and loan officers that he has never been charged with a crime, or had a crime expunged from his record. Under the law, it will be as though the arrest and trial never happened.

People convicted of crimes in New Hampshire are able to apply for an annulment after serving their sentence and demonstrating they have not been charged with new crimes. However, annulments are not available to people convicted of serious violent crimes. But, since Millar was found not guilty of Rothe’s second-degree murder, he is not bound by the same restrictions as those who were convicted of a crime.

Millar was accused of pressing his knee into Rothe’s back for several minutes after Rothe was handcuffed and placed in a prone position on his stomach. But the jury took less than two hours to find him not guilty after serious problems with the prosecution’s case were exposed during the three-week trial.

The state’s case hinged on the testimony of former Corporal Lesley-Ann Cosgro, the only officer to testify Millar kneed Rothe after he was handcuffed. But jurors heard testimony that Cosgro’s official story changed multiple times before the trial.

Rothe, 50, died on April 29, 2023, after fighting with several corrections officers who were attempting to remove him from a SPU day room. Cosgro was the officer in charge that day and ordered the room extraction that went wrong. Millar, who was not part of the original extraction team, came to help after hearing radio reports the team was in danger from Rothe’s attacks.

Cosgro initially made two statements to her DOC superiors after Rothe’s death, and in neither statement did she mention Millar’s knee or make any other accusations about excessive force. But when talking to State Police detectives, Cosgro claimed Millar put his full weight onto Rothe’s back for up to several minutes.

But, while testifying under oath at the trial, Cosgro said Millar’s knee was present for “seconds, flashes of seconds.”

During her cross-examination during the late June trial, Cosgro tried to deflect when defense attorney Jordan Strand pressed her on why, weeks later, she told State Police that Millar had his knee on Rothe’s back for several minutes.

“I’m not going to jail for killing this guy,” Cosgro told state police investigators, according to the transcript of her statement.

Cosgro violated several DOC policies when she led the extraction team the day Rothe died. The team she assembled did not have enough staff, Cosgro did not have staff members put on protective gear, and she did not assign extraction duties to the members of the team, among other failures. During the violent confrontation with Rothe, Cosgro used her taser several times despite DOC policy limiting its use to three times during extractions.

Before she met with State Police investigators in 2023, Cosgro was rattled by the ongoing criminal investigation as well as the fact she got a subpoena to appear before a grand jury. During Millar’s trial, Strand said Cosgro was scared of getting blamed for Rothe’s death for her own documented failures in the incident.

“You thought they were going to pin the death on you,” Strand said to Cosgro.

After Millar was arrested in February of 2024 for Rothe’s death, Cosgro changed her story again. Called to speak on the record with now former Department of Corrections Commissioner Helen Hanks in the spring of 2024, Cosgro backed off the length of time Millar supposedly kneed Rothe, telling Hanks it was down to seconds.

Cosgro’s 2024 interview with Hanks resulted in a disciplinary letter for her policy violations during the room extraction and for lying during the subsequent investigations. Strand read from the letter during the trial, stating that Cosgro “demonstrated significant inconsistencies in [her] statements” in the Rothe investigation.

But the evidence that Cosgro changed her story in 2024 had been held back from Millar’s defense team for at least a year. It wasn’t until days before the trial was originally set to start in March that thousands of pages of evidence was finally handed over.

Among the evidence the DOC originally held onto were emails demonstrating that Hanks herself had been told by the Attorney General’s Office to not conduct interviews with Cosgro or any of the other witnesses.

Before Millar’s case was sealed as a result of the annulment, InDepthNH.org obtained a letter from the New Hampshire Attorney General’s Office indicating Cosgro’s testimony was under review.

On June 26, after Cosgro’s testimony concluded, New Hampshire Attorney General’s Office Criminal Justice Bureau Paralegal Autumn Sayball sent a letter to the court requesting the full audio of Cosgro’s testimony.

“This office is requesting a copy of the June 20, 2025 audio testimony of Leslie-Ann Cosgro in regards to the above-captioned matter, with Judge St. Hilaire presiding,” Sayball wrote.

There was no public record that the Attorney General’s Office requested audio from any other witness testimony before Millar’s case was sealed.

This article first appeared on InDepthNH.org and is republished here under a Creative Commons license.