 -- Investigators with the FBI today questioned Enrique Marquez Jr., the man who originally purchased the two “assault-style” rifles used in last week’s San Bernardino shooting in which 14 people were killed, according to law enforcement officials briefed on the probe.

Authorities have been trying to talk to Marquez, 24, since the weapons were first traced to him, but could not until today because he was being evaluated for an unspecified health care issue, the officials said.

Marquez, who used to live next door to San Bernardino shooter Syed Rizwan Farook in Riverside, California, purchased the guns back in late 2011 and 2012, officials said previously, but it is not known if he played any role in Wednesday’s massacre. FBI Director James Comey said Friday that the gun buyer, who was not publicly identified at the time, was not then considered a suspect in the attack.

When asked today about Marquez’s status, FBI Assistant Director in Los Angeles David Bowdich told reporters he was "not prepared to discuss Mr. Marquez at this point."

Around the same time Marquez bought the long guns, Farook personally purchased the two other weapons, both handguns, that years later were used in the deadly assault on San Bernardino’s Inland Regional Center, officials said. Police said last week that all four weapons were purchased legally, but it is unclear how Marquez’s guns ended up in the hands of Farook and his wife, Tashfeen Malik, during their rampage.

When ABC News visited Marquez’s home this weekend, a makeshift sign in the yard said to “keep off” the property. Neighbors who spoke to ABC News said Marquez and Farook were longtime friends, but the relationship appeared to have grown more distant as Farook became more conservative recently.

An individual associated with a local mosque, who asked not to be named, said Marquez started coming there three or four years ago, after he had converted to Islam. The person said Marquez was shy and polite, but did not seem that bright. Two members of Farook’s family, but not Syed Farook, attended the same mosque, the person said.

Marquez previously worked at a Wal-Mart, and before that was employed by the California Department of Food and Agriculture, federal officials told ABC News.

Allan Lengel is a freelance journalist based in Washington, D.C. and reporter for the law enforcement news website TickleTheWire.com

[Editor’s Note: A previous version of this report said Enrique Marquez was 29 years old. This report has been updated to reflect new information in public documents that indicate Marquez is 24 years old.]

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