ST. PETERSBURG — William John Shutt once shot up an antique store with an AK-47 semiautomatic rifle while drunk back in 2013. More recently, he was suspended from Facebook for trolling strangers.

This is the man St. Petersburg police say shot two men in the Historic Old Northeast on March 27, killing one and wounding the other.

Shutt, 31, was arrested days later on charges of first-degree murder and attempted murder. Detectives obtained a search warrant on April 24 for his cell phone, looking for information that could explain his motivation.

The warrant reveals new details about the case, including the survivor's account of the shooting, hints of Shutt's volatile past and how detectives tracked him.

Ex-wife Kelly Euston, 24, said she and her family were "shocked but not surprised" when they heard about the deadly shooting.

"He's always had that weird demeanor that something is just not right about him," she said. "He was just sketchy."

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Euston said she met Shutt when she was in high school in Delaware. He already had served in Iraq and Afghanistan, she said. The Army confirmed he was a member of the National Guard.

Their marriage was short-lived. After the wedding, Euston said she discovered he was previously arrested in a shooting incident and was secretly using their wedding money to pay off his court fines.

The incident was also described in the St. Petersburg search warrant: Shutt fired the rifle at a store in Newark, Del., but told police he was drunk at the time and didn't know why he did it.

THE VIDEO: Vehicle seen fleeing after fatal shooting in St. Pete's Old Northeast

THE ARREST: Man arrested in fatal road rage shooting in St. Pete's Old Northeast

Their relationship deteriorated. He drank and didn't have a job, she said. He yelled a lot and once pushed her against the wall during a heated argument. On a 2014 road trip to Louisiana, she said Shutt exploded after he missed an exit.

"He did definitely exhibit road rage," Euston said. "He started taking the car and swerving all over the road and yelling."

They separated four months after the wedding, in 2014. For a while, she still followed him on Facebook.

"He just was mean to people," she said. "If he had something bad to say about them, he would always say it, no matter what."

Euston lost track of her ex-husband. She just knew he moved to Florida.

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Quentin Hicks, 42, was driving a black BMW convertible with the top down on March 27, just after 4 p.m. on a Wednesday. He and Tyler Oliverbrooks Acker, 31, were on their way to pick up Acker's father from a construction job in the Historic Old Northeast neighborhood. But they got lost.

Then they encountered Shutt, the warrant said. He was driving a blue 2012 Hyundai Santa Fe.

First the Hyundai driver was "taunting" them at a stop sign, Acker told police. They had the right of way, but the SUV kept stopping and braking into the intersection. A few blocks later, the Hyundai rolled up next to their convertible. The driver lowered his window and stared at them, Acker said, then cut off the BMW.

Soon after, Hicks pulled up next to the Hyundai at Bay Street NE and yelled "you cut us off, you saw the stop sign."

The Hyundai driver pulled out a black .380-caliber Ruger LCP pistol and fired at them, according to the warrant. Police would find seven shell casings.

Hicks was struck several times. One round went through Acker's leg. Hicks lost consciousness and struck a tree at the corner of 20th Avenue NE and First Street NE. He died at the scene. Acker was taken to the hospital.

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Acker was bleeding profusely and in pain when detectives visited him in the hospital. He told them what happened and what the shooter looked like.

Detectives also found surveillance video in the neighborhood that captured the shooting and the Hyundai driving off.

The video also captured a sticker on the back of the car, which led them to the doorstep of Kira Evelyn Linde, 25, on March 29. She was Shutt's girlfriend, and he was driving her Hyundai.

She said she loaned it to him the day before the incident, according to the warrant. When he came to pick her up from nannying on March 27 — the day of the shooting — she said he seemed extremely agitated. He asked her to drive and leaned the passenger seat far back.

Linde watched the surveillance footage and said the driver looked just like her boyfriend. He had the same hairline and same color shirt, she told police.

She said Shutt owns several weapons and buys and sells guns "a lot." She also said he had been recently suspended from Facebook for trolling strangers, making inappropriate comments on their pages.

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Detectives obtained a search warrant for Shutt and his apartment. They found him on April 2, walking the dog for a man who employs him as a caregiver.

Shutt was armed, police said, carrying a Glock pistol in his pants, though the warrant said he did not have a license to carry a concealed weapon. Shutt's employer let them search his condo, including a guest room Shutt used.

Inside, police said they found an AK-47 rifle, handguns and ammunition — including three magazines for a Ruger LCP pistol. Two had .380-caliber bullets, the same caliber used in the shooting. One magazine was empty.

Detectives did not arrest Shutt. But they kept him under surveillance.

Soon, Linde called detectives. She had changed her locks to keep her boyfriend out. But her surveillance system showed he had just entered her apartment without her permission. Police arrested him on a burglary charge on April 3.

Shutt then "broke down sobbing," according to the warrant, and confessed to the shooting.

Where was the murder weapon? Shutt told police he threw away the Ruger in the men's rest room of the North Shore Park Tennis Courts at 445 10th Ave. NE.

By the time detectives got there, the trash had been collected and destroyed.

Times senior news researcher Caryn Baird contributed to this report. Contact Kavitha Surana at ksurana@tampabay.com. Follow @Ksurana6