DEXTER, Maine — Nearly one year ago, on the morning of June 13, Steven Lake used a Remington model 11-87 12-gauge semiautomatic shotgun with a five-round capacity to kill his estranged wife, Amy, and his two children, 13-year-old Coty and 12-year-old Monica, before turning the gun on himself.

Lake pulled the trigger, but a group of former Maine police officers is still pressing its contention that local law enforcement holds some responsibility in the killings because it failed to secure his firearms following a domestic violence incident the year before. The group, led by Westbrook native Brian Gagan, who now lives in Arizona and has worked as a patrol officer in Westbrook and Scarborough, continues to push for reforms.

Over the past several months, Gagan has peppered state authorities with emails and other communications demanding that those he claims are partly at fault be called to account.

The Piscataquis County Sheriff’s Office and state authorities maintain that police couldn’t have prevented the events of June 13 and that state laws and policies are improving safety for domestic violence victims.

In November 2011, Gagan and three other former officers released a “Psychological Autopsy of June 13, 2011 Dexter, Maine Domestic Violence Homicides and Suicides,” which suggested that the killings might have been averted if local law enforcement and court officials had handled the case differently.

“Four people are dead because Steven Lake made a choice to end their lives,” Deputy Attorney General William Stokes wrote in a May 10 letter responding to an email from Gagan. “The ultimate responsibility for these deaths lies only with Steven Lake.”

Lake, an avid gun collector who owned 22 firearms, was a jealous, controlling husband, according to the report. His marriage to Amy began to fall apart, and in 2009 Lake reportedly told his son that he could get “a 29-cent divorce” — the cost of a bullet — from Amy.

Amy and Steven Lake’s troubled relationship boiled over on June 14, 2010, at 9 Brighton Road in Wellington when Steven allegedly brandished a gun in front of his family, threatening Amy and the man with whom he accused her of having a relationship.

The Piscataquis County Sheriff’s Office arrested Lake the next day and confiscated a pistol that was in his vehicle.

After the arrest, Amy Lake turned over Steven’s arsenal of weapons to family members because she didn’t want them in the home. She thought she had turned over all of Steven’s guns, but the two firearms he brought to the scene of the murders were not among the firearms given to family members, according to investigators.

On July 21, 2010, Dover-Foxcroft police Detective Scott Arno, on behalf of the Piscataquis County District Attorney’s Office, served Lake with a protection from abuse order issued by District Court Judge Kevin Stitham.

That order, under state statute, barred Lake from possessing any firearms and ordered him to turn his weapons over to police or another individual within 24 hours. In such cases, if the guns are given to someone outside the police department, the defendant must file a list of weapons and where they were surrendered to the court.

If the court sees probable cause to believe the defendant has weapons that haven’t been turned over, it may issue a search warrant, according to statute.

Gagan argued that police failed to follow through on the protection from abuse order.

“There was no best effort, there was no attempt to collect these firearms,” he said in a telephone interview Thursday.

“Four people are now dead as the result of the seismic law enforcement malfeasance,” Gagan wrote in an email addressed to Maine Attorney General William Schneider and Gov. Paul LePage.

At least two or three police officers should have gone to Steven Lake’s residence after service of the protection from abuse order and instructed him to turn over any weapons inside or anywhere on the property, Gagan argued, adding that if officers suspected Lake of lying about the number of weapons he had, they should have sought a warrant to search the home and the surrounding area.

By not doing so, the department violated the court order, Gagan said.

Sheriff’s Lt. Robert Young said that officers couldn’t have searched Lake’s residence and didn’t have grounds to obtain a warrant to search for weapons that might not have been accounted for.

He said that on the day of Steven Lake’s arrest, Amy Lake told officers that she already had given a family member all the weapons she knew Steven to own.

Young said that when he talked to Steven Lake in jail after his arrest for the domestic violence incident, he asked Steven if he had any other weapons, but Steven told him Amy had turned all his guns over to family, and the sheriff’s office believed that was the case.

Lake never provided the court with an inventory of his weapons, as state statute requires when guns are surrendered to someone other than police, and the court never issued a warrant allowing police to search for or seize firearms at Lake’s residence, workplace or other properties where he might have stored guns that Amy didn’t know about, according to Stokes.

Gagan said Arno served Lake with the protection from abuse order in July 2010 while Lake was away from his residence.

Young said he wasn’t sure if Arno asked Lake if he had other weapons when he served him with the protection from abuse order. Arno could not be reached for comment Friday afternoon.

Young said it is neither possible, nor constitutional, for an officer to search or obtain a warrant to search a residence based on feelings and suspicions that a defendant might be hiding something.

“If it were, every drug dealer in this state would be locked up,” Young said.

“It’s a complicated circumstance,” the lieutenant said.

Gagan said that under state statute, police need only to show an “articulable suspicion that firearms are still accessible by the [domestic violence] defendant.”

Stokes said Amy Lake gave 20 of Steven’s guns to family members and police confiscated another, but because Steven did not keep a list of his firearms, police could never have been sure that every weapon was accounted for.

Stokes was at a trial on Thursday and Friday and was not available for comment, but in the letter he sent to Gagan on May 10, he defended the sheriff’s department.

“The guns taken out of the Lake home and from Steven Lake were not taken pursuant to the Protection from Abuse Order, but as a result of Amy’s desire to have the guns removed from the home,” Stokes wrote. “One can only conclude that Amy believed she and the children would be safer if Steven was aware that a family member, rather than law enforcement, held his firearms.”

Gagan argued that police could easily have inventoried, if not seized, all the weapons removed from the Lake household and given to family members, but he said the sheriff’s department never took that step.

The Maine Domestic Abuse Homicide Review Panel released a report in April that acknowledged that domestic abusers with access to unsecured firearms present a direct threat to everyone in their household.

“The panel observes that law enforcement cannot readily identify possession of, or access to, firearms by a person who may be prohibited from possession of firearms pursuant to a protection order or bail conditions,” the report states.

Moreover, the panel said, law enforcement faces “several unique challenges” when it comes to securing and storing these firearms, and it is “impossible” to be sure that a person has relinquished all of his guns.

The panel recommended the formation of a task force, including law enforcement personnel, judicial officials, prosecutors and other stakeholders, that would examine how weapon seizures are handled in protection from abuse cases.

Assistant Attorney General Lisa Marchese served as chairwoman on the panel. Brenda Kielty, spokeswoman for the attorney general’s office, said the office supports the panel’s findings.

Gagan argued that a task force would only create an extra step that would complicate and slow the process of reforming how law enforcement in the future handles the seizure of firearms from people with protection orders against them.

Gagan suggested that Maine police officers should be better trained in how to handle domestic violence cases in which the defendant owns weapons. He said law enforcement agencies should be aggressive and active in finding and securing firearms.

He also said quicker trials are needed in these cases. Thirteen months passed between June 14, 2010, when Lake allegedly brandished a handgun and threatened his family, and his scheduled court date in July 2011. Lake killed his family just 22 days before he was set to appear in court.

The Lake killings could get a lot of attention in coming weeks, with two national television news programs expressing interest in airing segments on the tragic domestic violence case sometime in June, according to Gagan. He said he couldn’t say what the programs were at this time.

Gagan said he has seen some progress toward stemming future domestic violence homicide incidents, mostly in the form of bail reform enacted through LD 1867, “ An Act to Protect Victims of Domestic Violence,” which LePage signed into law on April 17.

Among other changes, the new law stipulates that judges, not bail commissioners, determine bail in cases in which domestic violence is alleged.

Steven Lake had been bailed out twice within a year after arrests related to domestic violence and to his violation of the protection from abuse order — at a cost of just $4,000 total.

Gagan said he is still frustrated by the lack of movement on ensuring that court-ordered weapon relinquishments are enforced.

Stokes argued that Gagan is trying to place undue blame on law enforcement for the killings, and that he is “ignoring the multitude of initiatives going on in the state right now, including new laws to keep victims safer.”

“It is my belief that your singular focus of blaming the Piscataquis County Sheriff’s Office for the deaths is misleading and inaccurate,” Stokes wrote in his letter to Gagan. “As is true in all tragedies, things could have been done differently and perhaps even better with the benefit of hindsight. To say the Lakes are dead due to law enforcement error is irresponsible. Only Steven Lake is responsible for the murders.”