Man who bought assault-style rifles for San Bernardino shooters was related by marriage and told friends before the attack there's 'Muslims in our own backyard just ready to go haywire' 

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The man who supplied guns to the couple who killed 14 people in San Bernardino, California, last week is connected to the shooters' family by marriage, state documents show.

Enrique Marquez, whose home was raided over the weekend and who is being questioned by federal investigators, was married last year to Mariya Chernykh, whose sister is the wife of Raheel Farook, brother of one of the shooters, Syed Rizwan Farook.

The family connection, revealed in marriage documents seen by Reuters, adds another element to the relationship between Farook and Marquez.

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Accused: Enrique Marquez, 29 (pictured), allegedly purchased assault-style weapons for the San Bernardino shooters years before the massacre

In laws: Marquez was reportedly related to shooters Syed Farook (left) and Tashfeen Malik (right) by marriage. Last year, Marquex married a woman who is sisters with the wife of Farook's brother Raheel 

Deadly: Above, the semi-automatic rifles and handguns used in the shooting, which resulted in the deaths of 14

Authorities have said Farook, 28, and wife Tashfeen Malik, 29, were radicalized Muslims who committed an 'act of terrorism' when they massacred 14 people on December 2.

On the night of the attack, Marquez posted an ominous message online and then checked into a psychiatric facility the next day.

Michael Stone, one of Marquez's friends, told Good Morning America that the Muslim convert made concerning statements in the lead up to the attack. 

'He said something along the lines of there's Muslims in our own backyard just ready to go haywire and attack and we didn't think nothing of it,' Stone said. 

Farook, the U.S.-born son of Pakistani immigrants, and Malik, who was born in Pakistan and spent much of her life in Saudi Arabia, died in a shootout with police several hours after the attack in San Bernardino, about 60 miles east of Los Angeles.

Two assault-style rifles used in the attack were legally purchased by Marquez, who has been described by several of his neighbors as having been a good friend of Farook, according to the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives.

Marquez posted this message just hours after the shooting in California. The day after the shooting, he checked himself into a psychiatric facility

Michael Stone (pictured), one of Marquez's friends, says he made a disturbing comment about Muslims ready to carry out attacks before the shooting 

Mysterious: Hours after the shooting which left 14 dead, Marquez checked himself into a mental health clinic

Some of Marquez's neighbors say they didn't know he was married, and that the only woman who seemed to live with him was his mother 

The Farook brothers lived next door to Marquez when they were growing up, though the brothers had both since moved.

Raheel Farook, the older brother and who became the brother-in-law of Marquez, served in the U.S. Navy, joining in 2003 shortly after graduating from high school.

Federal agents raided the Marquez home in Riverside, California, on Saturday. Marquez was being interviewed on Tuesday, a law enforcement official said. He had checked himself into a Los Angeles-area psychiatric facility following the shooting.

The marriage documents show that Enrique Marquez married Mariya Chernykh on November 29, 2014. It could not be determined whether they currently live together. Witnesses to the marriage were Mariya's sister, Tatiana Farook, and Tatiana's husband, Raheel Farook.

Raheel Farook married Tatiana, then known as Tatiana Gigliotti, on September 10, 2011, the documents show.

Search and seizure: FBI agents executed a search warrant at Enrique Marquez's home on December 5

It is unknown if the damage, including the smashed garage pictured above, occurred during the raid or prior to the raid

Shattered glass: Several windows of Marquez's home were also broken. A large black curtain and cardboard boxes were seen through one window

Ransacked? One of Marquez's neighbors said she saw enforcement break windows and use a torch to get in the garage

Two neighbors of Marquez told Reuters they never saw him with a woman.

'I saw no sign of him having a wife - it was only his mom in the house,' said Lori Aguirre, who lives across the street and said she knew Marquez because he sometimes drove her son to and from school.

'I only saw him going to work or coming home alone. It would be a big surprise if he was married,' she said.

This was echoed by another neighbor, who said he did not know Marquez. 'I never saw any young woman around. Only his mom,' said the man, who declined to be named.

A third neighbor, however, said he had seen Marquez with a woman. 'I don't know if they were legally married, but I saw him with someone,' said the neighbor, who also declined to be named.

Employees at a Walmart Supercenter in Corona, California, 20 minutes by car from Riverside, said Marquez has been working there as an asset protection and customer specialist for about six months. He was last seen at the store on November 29, they said.

Ashlee Sims, 25, a security guard at the Walmart, on Sunday described Marquez as 'weird' and 'awkward.' He is quiet, but likes to go out and party, Sims said.