The Warren man who fatally shot his fiancee and her brother — before turning the gun on himself — told family members he planned to kill police officers as well, according to a detailed sequence of events authorities released Thursday.

The Somerset County Prosecutor's Office, in a joint statement with Warren Township police, said John Reno told one family member “I’m going to kill a bunch of pigs." as he waited at his Mount Horeb Road home Aug. 16 armed with a GPI SLR15, 5.56mm assault rifle equipped with a detachable box magazine, adjustable stock, pistol grip, bayonet lug, an attached bipod and optical scope.

Reno's attack on his fiancee and her brother set off a lengthy standoff with police — though investigators now believe Reno himself was dead for much of that time.

His live-in fiancee's brother, Frederick Errickson Jr., 55, was dead in the driveway when police arrived, authorities have said. A remote-controlled robot found Heidi Errickson, 45, dead inside. Reno himself was found in a drainage ditch in a wooded area behind the home.

But Errickson had apparently been dead for some time — Reno took to social media to apologize and started calling family members the night before, according to the new breakdown of events, authorities said.

The prosecutor's office said investigators pieced together their account by talking to family and friends of the Erricksons, police audio recordings, social media and text message posts by John Reno, material that was recovered by crime scene investigators inside the residence, and the State Medical Examiner’s post mortem examinations.

"This was clearly an individual who possessed a strong desire, a stated willingness, and a very apparent ability to inflict tremendous harm on people," Prosecutor Geoffrey D. Soriano said Thursday. "I believe that I can speak on behalf of all law enforcement officers throughout Somerset County when I say that our hearts go out to the Errickson family for their losses.  Without the quick and brave action by the immediate responding officers and those officers who followed, the magnitude of the tragedy could have greatly expanded.”

The timeline as described by the prosecutor's office:

Reno and Heidi Errickson were involved in an argument during the evening hours of Saturday, Aug. 15 inside of the residence.  At some point during the argument, Heidi Errickson indicated she would call the police, but that call was never made, the prosecutor's office said.

Authorities said they can't know an exact timeline of events on Aug, 15, but at 10:32 p.m. John Reno made a post on a social media site: “I so sorry!!!!!!!!!!!” Reno then placed calls to family members "indicating what he had done as well as his desire and willingness to engage responding law enforcement officers," the prosecutor's office said.

He told one family member “I’m going to kill a bunch of pigs.” He then waited at the residence armed with a the assault rifle, according the the prosecutor's office.

The next day, Frederick Errickson Jr. arrived at the home at about 12:45 p.m. — but as he exited his vehicle and walked up the driveway, Reno opened fire from the porch, shooting 18 rounds, several of which fatally hit Frederick Errickson, the prosecutor's office said.

Warren Township Police got a call at 11:16 p.m. — the caller thinking Reno was involved in a shootout with police at the Mt. Horeb Road residence, the prosecutor's said. Two Warren Township police units were dispatched to conduct a welfare check on John Reno.

Two minutes later, a sergeant and a patrolman arrived and were met with a barrage of gunfire. They radioed that shots were fired and requested the Somerset County SWAT Team, the prosecutor's office said.

Reno had been firing from a concealed position in the kitchen, the prosecutor's office said. One round narrowly missed the sergeant’s head, and may be the one that traveled several hundred yards across the street, through an empty parking lot and became lodged in an unoccupied professional office building, the prosecutor's office said.

In all, Reno fired 20 rounds at the officers as they took cover behind a motor vehicle and a tree, it said. Officers from several agencies —Warren, Green Brook, Watchung, Bernards, and the prosecutor’s office — were the first to arrive to provide assistance, the prosecutor's office said. They helped the officers on the scene get to a position of safety.

Gabe Vallie and Heidi Errickson (Courtesy of the Beard Family)

Reno's weapon began to experience mechanical malfunctions and he dropped several live rounds on the ground trying to fix it — several were later recovered outside of the dwelling near the rear patio, near the front porch and grass area of the residence, and on the kitchen floor, the prosecutor's office said.

Also found in the kitchen: A 30-round magazine with more live ammunition. Another seven rounds and one live shell casing were later found near John Reno's deceased body, along with the assault rifle, which contained a large capacity magazine, the prosecutor's office said. Yet another large capacity magazine, loaded with ammunition, was located under his body.

Reno had slipped out while officers were establishing a permitter, the prosecutor's office said. Investigators later used audio recordings form the patrol cars to create a timeline of the gunshots — the last at 1:33, which investigators believe is the one Reno used to end his own life.

The Somerset County SWAT and Crisis Negotiations Team activation occurred at 1:30 p.m., according to the prosecutor's office. Authorities evacuated nearby homes and tried to contact Reno — not knowing at the time he was out of the home and dead by 1:33 p.m., authorities said. They found him when closing the perimeter after learning the Erricksons were dead.

Illegal weapon

The prosecutor's office notes Reno didn't have a New Jersey Firearms Identification card. Even if he did, his weapon would have been illegal in New Jersey.

New Jersey 101.5 noted in a report last week Reno had posted often on social media about his extreme disdain for gun control and distrust of politicians — including President Barak Obama — supporting it.

Heidi Errickson had seen more than her share of tragedy in her life, having lost her husband in a crash that also took her arm. And only weeks before the killing, she was celebrating her "amazing" life with Reno.

Family members said while they're devastated by the killings, their faith in humanity was kept alive by an extraordinary outpouring of support, including through a fundraiser that to date has raised nearly $60,000. Proceeds benefit Heidi Errickson's son's college education.

According to the prosecutor's office, several agencies were involved in the response.

• Bernards Township Police Department
• Bernardsville Borough Police Department
• Hillsborough Township Rescue Squad
• Long Hill Township Police Department
• Martinsville Rescue Squad
• Mt. Bethel Fire Department
• New Jersey State Police Aviation Unit (on standby)
• New Jersey State Police ROIC (Regional Operations Intelligence Unit)
• Peapack-Gladstone Police Department
• Somerset County CERT (Community Emergency Response Team)
• Somerset County Communications and Command Mobile Unit
• Somerset County EMS
• Somerset County EMS Coordinator
• Members of the Somerset County Police Emergency Response Plan (Eastern Region) consisting of: North Plainfield Borough Police Department, Watchung Borough Police Department, Green Brook Township Police Department and Berkeley Heights Township Police Department
• Somerset County Sheriff’s Office
• Somerset County Tactical Emergency Medical Services Team
• Somerville Rescue Squad
• Warren Township Volunteer Fire Department
• Warren Township Office of Emergency Management
• Warren Township Police K-9 Unit
• Warren Township Rescue Squad