DNA reveals identities of twins shot and set on fire along road. Two are accused of murder.

Emergency calls about a brush fire in rural Palm Beach County instead yielded a smoldering mystery to be recounted for a murder trial this week.

The case began 4½ years ago when first responders found two burning bodies wrapped in bedding and plastic in a grassy area about 20 feet from a highway.

Because DNA evidence wasn’t destroyed in the flames, investigators identified the shooting victims as 21-year-old twins Brandon and Brian Allen of West Palm Beach. More detective work led to first-degree murder charges against their roommates, Jullian Cathirell and Darin Byrd.

Prosecutors say these alleged assailants failed in attempts to cover up the killings, leaving behind plenty of convincing proof for jurors to convict both men. They will be tried separately, beginning with Cathirell, 26.

But attorneys for Cathirell have been preparing a self-defense claim to explain the violence, while a court-appointed lawyer for Byrd, 24, declined to reveal his trial strategy to the South Florida Sun Sentinel. Arrest reports tag Cathirell as the shooter, with Byrd a key part of the deadly confrontation and the botched cover-up.

Prosecutors have dropped plans to seek the death penalty for Cathirell; first-degree murder convictions for both men would bring automatic life in prison sentences.

On the evening of March 14, 2017, a meeting was called to discuss “household issues” inside the apartment on the 800 block of Millbrae Court.

There was tension in the air, as Brandon Allen and Cathirell had been in a feud for some time. An argument got heated, and Cathirell pulled a .45-caliber handgun and shot Brian Allen in the stomach and then Brandon in the right arm, according to a witness who was in the room and spoke with detectives.

Cathirell had good reason for using the weapon, said Assistant Public Defender Scott Pribble. Here’s how he explained it in a recent pleading:

“Based on the aggression, threats, and hostility by the Allen brothers toward Mr. Cathirell in the weeks leading up (to) them being shot — as well as their very vocal efforts to obtain a firearm to harm Mr. Cathirell during that time period — it appears that a prominent issue for the jury to resolve in the trial may be whether or not Mr. Cathirell was justified in using deadly force to defend against a perceived threat to his life.”

Pribble says the Allens shouldn’t be referred to as “victims” during the trial.

An arrest report states that Brandon tried to run toward the front door, “but Darin Byrd blocked him and prevented his escape and pushed him down to the ground.”

The unnamed witness went outside, heard two more gunshots, followed by Cathirell and Byrd walking out the door and announcing the twins were dead.

But during the investigation, Cathirell told an investigator that he had no idea what had happened to the Allens, and said he wasn’t home at the time of the shootings. Byrd said he was at the residence yet didn’t see or hear anything.

Pribble declined to comment about the case. Byrd’s lawyer, Barry Feingold, also said he didn’t want to discuss it; a trial date has not been set for Byrd.

Hours after the shooting, Cathirell and Byrd got to work on cleaning the apartment with bleach and alcohol, authorities say.

At 1:48 a.m., someone took a photo later found on Cathirell’s phone showing a pool of blood on the floor. Despite the cleanup efforts, blood samples from the floor came back as positive for Brandon’s and Brian’s DNA.

The witness told detectives that Cathirell and Byrd wrapped the bodies in sheets and plastic and kept them in a third-floor bathtub until that evening.

A plan was drawn up to dispose of the remains: Byrd and Cathirell would take Byrd’s girlfriend’s Toyota Corolla “on a drive” to the Beeline Highway and find a place to dump the bodies and burn them, records show.

Surveillance video at the apartment complex shows Byrd driving the car on the property at 8 p.m. and then leaving about 21 minutes later.

After 9 p.m., Cathirell called the witness to say the bodies were gone.

Within minutes, authorities received the first 911 call about the suspected brush fire. Prosecutors say the actions by Cathirell and Byrd to conceal the crime supports two tampering with evidence felony charges.

The Palm Beach County Sheriff’s DNA lab provided the identities of Brandon and Brian Allen. An autopsy determined that Brandon was shot in the arm and head, and Brian was shot in the torso and head.

The bodies “were observed to have significant ‘thermal changes’ due to being set on fire posthumously,” Pribble wrote as part of a request to keep the jury from seeing “gruesome photographs” of the bodies as well as autopsy photos.

The argument is that sharing such “emotionally evocative evidence” with jurors would be too prejudicial against Cathirell, he explained, suggesting Circuit Judge Jeffrey Dana Gillen could consider black-and-white photos as a possible alternative.

Once detectives had the victims’ identities, they searched their apartment and it became clear that’s where they were killed. Crime scene investigators took inventory of bloody towels and sponges, as well as cleaning liquids.

They also searched the Toyota’s trunk. Blood collected from inside the storage space matched Brandon’s DNA, the Sheriff’s Office said. Brandon’s blood was also found on a pair of sneakers that Byrd admitted were his.

The key to solving the case was the witness to the shootings, who said Cathirell threatened him not to speak with law enforcement.

Investigators didn’t recover the gun used to kill the Allens, but while searching Cathirell’s phone they found a photo of a handgun taken one day before the twins were shot.

Obituaries published online said the young men had worked as cooks at Chick-fil-A. Their parents died before the murders, and a sister is listed as a possible trial witness. Efforts to reach other family members were not successful.