Former State Police Trooper Michael Proctor invoked his Fifth Amendment right Monday, Sept. 14, at a hearing in a Milton murder case he once investigated.

Judge Peter Krupp allowed Proctor to stay silent after holding a sealed sidebar conference with Proctor and his attorney at Norfolk Superior Court in Dedham. The proceeding determines whether a witness has a valid privilege against self-incrimination. Proctor then walked out of the courthouse. His lawyer declined to comment.

The ruling landed in the middle of a defense push to dismiss murder charges against Myles Omari King, 26, who has pleaded not guilty to first-degree murder and weapons charges. King is charged with fatally shooting Marquis Simmons, 25, on the evening of July 10, 2021, on Belvoir Road in Milton.

Defense attorney Rosemary Scapicchio, who represents King, told reporters outside the courthouse that Proctor's attorney had twice indicated before the hearing that Proctor would not invoke the Fifth Amendment, then reversed course in the courtroom.

"Clearly, something exposed him to criminal liability," Scapicchio said.

Scapicchio has argued that Proctor's documented racism made it impossible for him to conduct a fair investigation of King, who is Black. Among the text messages included in her motion to dismiss, the Boston Herald reported, Proctor wrote about dragging a Black person from his bumper through the streets and burning a cross. In separate messages revealed during Karen Read's civil litigation, the Boston Globe reported Proctor told a Canton police officer not to rush to a crash scene because a Black person was hurt, using a racial slur.

Prosecutors acknowledged in a court filing that Proctor exchanged messages over many years showing bias against women, LGBTQ+ people, people with intellectual disabilities and multiple racial and ethnic groups. But they argued King has not shown any connection between those messages and the investigation or charges in this case.

Prosecutors also said Simmons identified his assailant before dying. Milton police knew the name Simmons gave, "Mizzie Cash," was King, according to the prosecution's filing. Phone records and video surveillance also link King to the crime, prosecutors said.

Proctor was fired from the Massachusetts State Police in March 2025 after a trial board found he violated four department policies during the Karen Read investigation. Read was acquitted of second-degree murder at her retrial in June 2025, convicted only of a misdemeanor drunken-driving charge. The fallout from that case exposed Proctor's text messages and prompted defense attorneys across the state to seek dismissals of cases he investigated.

Scapicchio said her case is not weakened without Proctor's testimony, noting he sat for a civil deposition that may contain relevant information. She also said Proctor might not invoke the Fifth if the case reaches trial.

An evidentiary hearing on the motion to dismiss is scheduled for Tuesday, Sept. 22. Retired State Police Lt. Brian Tully, who oversaw the Read investigation, is expected to return to the stand. Milton police officers and a defense expert on bias are also expected to testify.