Weeks after a mistrial was declared in the high-profile murder case of Karen Read, more allegations of police misconduct surfaced in the same Massachusetts county where a former police detective was charged in the 2021 death of a pregnant woman, placing a renewed spotlight on the relationship between police and prosecutors.

Criminal justice experts say the two cases appear to involve investigative missteps that highlight the need to scrap the Massachusetts model of investigating high-profile crimes.

“Understatement of the century but Massachusetts has a serious problem with murder investigations involving police suspects, witnesses, and leads,” criminal justice journalist Susan Zalkind posted on X on Wednesday. “Poor Sandra Birchmore. Beyond depraved.”

Federal prosecutors allege former detective Matthew Farwell groomed Birchmore, 23, and began sexually abusing her as a teen, when he worked with the Stoughton Police Explorers Academy, a youth program she was in. He was arrested Wednesday, with prosecutors alleging he killed Birchmore, who had told him she was pregnant with his child, and attempted to stage the scene as a suicide so that the sexual abuse allegations would stay hidden.

Farwell has pleaded not guilty.

Birchmore was killed in Canton, the same Norfolk County town where Boston police officer John O’Keefe, 46, was found dead on Jan. 29, 2022. His girlfriend, Read, was tried in his death. A jury failed to reach a verdict after her legal team argued that Read had been framed by other law enforcement officers attempting to cover up O’Keefe’s death. She will be retried next year on the charges.

Federal investigators have been involved in both cases, but officials have not announced any links between the two. However, at the heart of both: allegations of botched investigations and law enforcement misconduct.

‘Incompetence or corruption?’

“Given these two cases, I would say it’s not just in Norfolk County, but certainly throughout Massachusetts. The question that arises is, is it incompetence or corruption, or both?” said Tom Nolan, a former Boston police lieutenant and criminal justice professor.

In Massachusetts, detectives with the state police are assigned to district attorneys’ offices, which can lead to the bungling of cases, Nolan said.

An alternative, he said, is the model used in other states, including Florida and Georgia, where there is an independent investigative agency to oversee the cases, rather than relying on an agency that enforces laws on highways.

“We saw on full display for several weeks during the Karen Read trial, the bumbling incompetence of the Massachusetts State Police, who were assigned to the Norfolk DA’s Office. Her defense counsel just basically eviscerated the State Police troopers who were testifying as witnesses and experts, — ‘expert witnesses.’ Their credibility was completely undermined,” Nolan said.

State police did not respond to requests for comment.

Hours after a mistrial was declared in Read’s trial, the top official at Massachusetts State Police said the lead detective in the case had been relieved of duty after allegations of “serious misconduct” were raised in court.

After the agency launched an internal affairs investigation into the allegations, the detective was suspended without pay last month.

Zalkind, who wrote “Waltham Murders: One Woman’s Pursuit to Expose the Truth Behind a Murder and a National Tragedy,” which focuses on a Massachusetts triple-slaying and the Boston Marathon bombing, told NBC News that without an independent investigative agency and proper checks and balances, prosecutors and police can get too cozy and politics can come into play.

“When you imbue that culture to the good old boys’ club, to homicide cases, there are serious issues,” she said. “Our homicide investigations are politicized. The DAs in the state, all except for one are Democrats. Our AGs are Democrats. … Our government is Democrat. So there is a lack of incentive to do a vigorous follow-up.”

No matter what the legal outcomes in the Read and Birchmore cases, public trust has been compromised, said Zalkind.

A staged suicide

In announcing the charge Wednesday more than three years after Birchmore’s death, acting U.S. Attorney Joshua Levy called the arrest of Farwell, a police officer who swore to protect the public, “disheartening.”

Farwell is charged federally with one count of killing a witness or victim.

“Giving voice to the voiceless, ensuring that no one is above the law, protecting the vulnerable people of Massachusetts, that’s the highest calling of people in law enforcement,” Levy said. “Mr. Farwell violated those principles, and now he faces very grave consequences.”

Farwell’s attorney could not be reached for comment.

State police initially handled the investigation into Birchmore’s death. Nolan said it’s “strikingly unusual” that the case was taken over by federal authorities because homicides are usually prosecuted as state crimes.

Federal authorities did not elaborate on why they took the case, except to say investigators had received new evidence that made the indictment and arrest possible.

David Traub, a spokesperson for the Norfolk District Attorney’s Office, said the office has long been working with other law enforcement to secure an arrest.

“This office has been collaborating with both the Massachusetts attorney general and the FBI for months on investigations into the Birchmore matter. Two of our detectives were present at the command post … while federal authorities were attempting to take Matthew Farwell into custody,” Traub said.

“Much of the information that they [federal authorities] built on originated with our investigation, including the collection of thousands of text messages, and then going through those text messages to see what criminal conduct might be substantiated from their contents,” he said.

Prosecutors allege that Farwell killed Birchmore on Feb. 1, 2021, in her apartment, when he could no longer control her and as word began to get out that he had been having sex with her for years. Authorities initially ruled Birchmore’s death a suicide.

Prosecutors contend that after Farwell strangled Birchmore, he repositioned her body and staged her apartment to look as if she had died by suicide.

The medical examiner determined Birchmore’s death was a result of “asphyxia by hanging” and she was eight to 10 weeks pregnant when she died, according to an affidavit in support of the motion to detain Farwell.

The Massachusetts Office of the Chief Medical Examiner, which made that finding, did not respond to a request for comment Friday. A spokesperson for the agency told WFXT-TV of Boston that the office was aware of Farwell’s indictment and had cooperated with the U.S. Attorney’s Office.

An expert retained by federal prosecutors, Dr. William Smock, concluded the death was a homicide, arguing that some of Birchmore’s injuries are more common in cases of strangulation than hangings, like abrasions on Birchmore’s nose, the affidavit said.

Farwell’s arrest came nearly two years after Stoughton’s police chief announced that Farwell and two other former officers at the agency had inappropriate relationships with Birchmore. That conclusion came from a lengthy internal affairs investigation prompted by Birchmore’s death, said Chief Donna McNamara, who called the former officers’ behavior “deeply disturbing.”

The chief said all three men resigned before they could be interviewed. The department recommended that their certifications as police officers be permanently revoked so they cannot serve in law enforcement anywhere in the country, McNamara said.

Lawyers for the other former officer did not immediately respond to requests for comment about the status of their decertifications.

Questions in Read investigation 

After a nine-week murder trial that captured national attention, a judge declared a mistrial for Read on July 1.

Prosecutors have said the relationship between Read and O’Keefe was deteriorating when she plowed into him with her SUV. She was charged with second-degree murder, motor vehicle manslaughter while driving under the influence, and leaving the scene of a collision causing death.

She has maintained her innocence and is set to face another trial early next year. An attorney for Read did not respond to a request for comment Friday.

The Norfolk District Attorney’s spokesperson said prosecutors are preparing for Read’s upcoming trial, and that the only appropriate forum for determining her innocence or guilt is a courtroom.

No federal charges have been filed in the case.

During the original trial, Read’s lawyers said she watched her boyfriend enter the Canton, Massachusetts, home of a now-retired Boston police sergeant for a party after a night out with other current and former law enforcement officers. Hours later, the defense team said at trial, she discovered O’Keefe had never come home and raced back to the house, where she found his body.

Read’s lawyers have alleged that O’Keefe was most likely beaten inside the home and left outside in the snow.

The defense has blamed authorities for failing to carry out a “real” investigation and instead focusing on Read.

They have alleged the lead investigator in the case, Massachusetts State Police Trooper Michael Proctor, was one of the chief reasons the investigation was biased. They say he manipulated evidence and made derogatory comments about Read.

Proctor has denied the allegations and said his comments were unprofessional and regrettable but they didn’t compromise the case.

Proctor has not responded to requests for comment.

This article was originally published on NBCNews.com