CORRECTS THE NAME OF THE SOURCE TO THE MIDLAND REPORTER-TELEGRAM - Odessa and Midland police and sheriff's deputies surround the area behind Cinergy movie theater in Odessa, Texas, Saturday, Aug. 31, 2019, after reports of gunfire. Police said there are "multiple gunshot victims" in West Texas after reports of gunfire on Saturday in the area of Midland and Odessa. (Tim Fischer/Midland Reporter-Telegram via AP)
Tim Fischer/Midland Reporter-Telegram/AP
CORRECTS THE NAME OF THE SOURCE TO THE MIDLAND REPORTER-TELEGRAM - Odessa and Midland police and sheriff's deputies surround the area behind Cinergy movie theater in Odessa, Texas, Saturday, Aug. 31, 2019, after reports of gunfire. Police said there are "multiple gunshot victims" in West Texas after reports of gunfire on Saturday in the area of Midland and Odessa. (Tim Fischer/Midland Reporter-Telegram via AP)
Now playing
01:32
What we know about deadly shooting in Odessa, Texas
Courtesy Rosie Granados
Now playing
02:33
Slain mail carrier's twin sister recounts their last call
Abbott on text
KOSA
Abbott on text
Now playing
01:31
Governor: Toddler-victim's mom just texted me this
KOSA
Now playing
01:44
Witness recounts coming face-to-face with suspected gunman
Beto
CNN
Beto
Now playing
01:01
Beto O'Rourke: This is f***ed up
odessa texas mass shooting police confrontation vpx_00000000.jpg
Joey Vicknair
odessa texas mass shooting police confrontation vpx_00000000.jpg
Now playing
00:42
Witness films police appearing to confront shooter
kosa-tv local news station evacuated odessa midland texas shooting vpx_00000000.jpg
KOSA-TV
kosa-tv local news station evacuated odessa midland texas shooting vpx_00000000.jpg
Now playing
00:58
Odessa news station evacuated mid-broadcast due to shooting
Ambulances outside Medical Center Hospital in Odessa, TX on August 31.
KMID
Ambulances outside Medical Center Hospital in Odessa, TX on August 31.
Now playing
02:18
'Surreal' video captures gunfire in Odessa, Texas
A woman cries during a candlelight vigil for the victims of the Wednesday shooting at Marjory Stoneman Douglas High School, in Parkland, Fla., Thursday, Feb. 15, 2018. Nikolas Cruz, a former student, was charged with 17 counts of premeditated murder on Thursday. (AP Photo/Gerald Herbert)
Gerald Herbert/AP
A woman cries during a candlelight vigil for the victims of the Wednesday shooting at Marjory Stoneman Douglas High School, in Parkland, Fla., Thursday, Feb. 15, 2018. Nikolas Cruz, a former student, was charged with 17 counts of premeditated murder on Thursday. (AP Photo/Gerald Herbert)
Now playing
03:59
The cycle of inaction after mass shootings
Crime scene tape surrounds the Mandalay Hotel (background) after a gunman killed at least 50 people and wounded more than 200 others when he opened fire on a country music concert in Las Vegas, Nevada on October 2, 2017. 
Police said the gunman, a 64-year-old local resident named as Stephen Paddock, had been killed after a SWAT team responded to reports of multiple gunfire from the 32nd floor of the Mandalay Bay, a hotel-casino next to the concert venue. / AFP PHOTO / Mark RALSTON        (Photo credit should read MARK RALSTON/AFP/Getty Images)
MARK RALSTON/AFP/Getty Images
Crime scene tape surrounds the Mandalay Hotel (background) after a gunman killed at least 50 people and wounded more than 200 others when he opened fire on a country music concert in Las Vegas, Nevada on October 2, 2017. Police said the gunman, a 64-year-old local resident named as Stephen Paddock, had been killed after a SWAT team responded to reports of multiple gunfire from the 32nd floor of the Mandalay Bay, a hotel-casino next to the concert venue. / AFP PHOTO / Mark RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images)
Now playing
01:25
These are the deadliest mass shootings in modern US history
(CNN) —  

Federal investigators on Wednesday searched a Texas home as part of the investigation into the sale of a weapon used in a shooting rampage that killed seven people and wounded 25, two law enforcement officials told CNN.

The home in Lubbock is associated with the alleged seller of the firearm used by the gunman, who went on a killing spree in and around Odessa, an official said.

The investigation into the gun sale highlights one of the loopholes in the patchwork of federal gun laws. Because the sale was a so-called private sale, the seller isn’t required to conduct a background check on the buyer, which is required in sales by licensed gun dealers.

Authorities are seeking to determine whether the sale violated federal law, which requires that sellers register as gun dealers if they’re buying and selling guns for profit and acting essentially as gun dealers.

The gunman failed a background check during an attempted firearm purchase in 2014 because he had earlier been adjudicated “a mental defective” and temporarily committed to an institution, three law enforcement sources told CNN on Wednesday.

Seth Ator, 36, had been committed to an unidentified institution in McLennan County in 2006 because he was deemed a danger to himself and/or others, according to one source.

The commitment occurred more than a decade ago, a second source said.

Still, Ator managed to buy the firearm used in Saturday’s mass shooting within the last couple of years, according to a third source. Police said Ator used an AR-15-style rifle. He was killed by police.

A mental defective” is a term used in federal law to describe one category of people prohibited from purchasing or owning a firearm.

Ator tried to buy a firearm on January 14, 2014, but wasn’t allowed to, the Texas Department of Public Safety told CNN in an email.

The department is prohibited by law from disclosing the reason he was denied the purchase, the DPS said.

’Suicidal tendencies’

In July 2001, Ator was charged with criminal mischief after breaking a window at the DePaul Center, a psychiatric and drug abuse facility in McLennan County, according to Tom Needham, the county’s executive assistant district attorney.

The DePaul Center requested that the charge not be prosecuted, the prosecutor said.

“He paid for the window and apparently they asked that it be dropped,” said Needham.

The prosecutor said he could not confirm that Ator was committed to the DePaul Center, only that the criminal mischief charge stemmed from him having broken a window there.

Ator did receive an “evaluation for suicidal tendencies” at the DePaul Center in 2001, and his father reported that Ator had made “suicidal threats and attempts,” according to a McLennan County Sheriff’s Office arrest report.

Additionally, in July 2001, a Lorena, Texas, woman complained that Ator had threatened her son’s life following “a series of problems” that involved Ator and his relationship with a female member of the woman’s family, according to the arrest report.

A photo of Seth Ator released by the city of Odessa.
City of Odessa, TX
A photo of Seth Ator released by the city of Odessa.

An officer issued a criminal trespass warning to Ator that month, according to the report, but a few weeks later Ator returned to the family’s home at 3:30 a.m. and removed a bedroom window screen.

The following day, an officer went to an apartment where Ator was staying, but Ator jumped out the bedroom window from the second floor and escaped, according to the report.

Ator was charged with criminal trespass and evading arrest, according to the sheriff’s department documents.

Needham told CNN Ator received 24 months deferred adjudication probation, drug and alcohol testing as well mandatory attendance at Narcotics Anonymous.

Needham added, “Mental health records are confidential, but I am not aware of any records concerning mental health adjudications or commitments.”

’He just snapped’

In June 2012, Ator was arrested and charged him with public intoxication after he got in a fight, said Larry Adams, assistant chief of police for the city of Woodway, Texas.

Adams said witnesses told police Ator had been “drinking all night” and that one person head-butted him, leaving cuts on his face and nose. The charge is a Class C misdemeanor, which Adams said may not show up in court record searches.

Brandon Hart, a former friend of the gunman, said Ator took a knife and swung it at another person at the house. “It was like he just snapped… He became very paranoid and angry,” Hart said, adding, “I just thought, wow, that was insane.”

Hart said he and others at the party were unable to calm Ator down and that the fighting escalated.

Hart described Ator as “generally reserved and quiet. He didn’t seem to have a whole lot of friends.” He said Ator was nice but also seemed lonely.

Kyle Douthit, who described himself as a longtime acquaintance of Ator, told CNN Ator believed “the whole world was against him.”

Douthit said Ator dealt with challenges throughout his life.

“He wasn’t a bad person. He just didn’t like the way people treated him. He would get paranoid,” Douthit said. “He always had this aggression when he was drinking. He would all of a sudden just think you were against him.”

When the troopers pulled Ator over Saturday, “I think he was just done,” Douthit said.

“He was probably just doing it the way he wanted to do it,” Douthit said. “I don’t think it had anything to do with anything going on in the world. It was just his world.”

The ATF, the FBI and the Texas Department of Public Safety are “aggressively following up on” the source that supplied the firearm that Ator used in last weekend’s rampage, according to the ATF.

Investigators are still searching for a motive in the mass shooting.

The man showed up to work Saturday “in a distressed mental state,” and was fired, said FBI Special Agent in Charge Christopher Combs.

Combs said the firing wasn’t the reason for the shooting spree and that he was “already enraged” when he showed up for work.

Ator had been “on a long spiral going down,” and he had “probably been in trouble for a while,” Combs said.

The shooting began Saturday when Texas Department of Public Safety troopers pulled Ator over for failing to use his turn signal, and Ator began firing at them. Speeding away, he went on to spray bullets as he drove west toward Odessa and into the city. At one point, he hijacked a US Postal Service truck, killing the mail carrier.

Ator was finally stopped in a parking lot after officers rammed the hijacked truck and gunned him down.

CNN’s Ed Lavendera contributed to this report.