REVEALED: Secret Service once arrested Waffle House killer, police previously confiscated his guns

Local and federal law enforcement knew the man who opened fire in a Tennessee Waffle House early Sunday morning, killing four and injuring at least seven others.

They knew him so well that he was arrested last year and had his firearms confiscated.

What are the details?

The Secret Service said Sunday its agents arrested the killer in July 2017 after he was found in a "restricted area" near the White House, according to the Tennessean.

Secret Service representative Todd Hudson said: "He wanted to set up a meeting with the president."

The killer, who is reportedly from Illinois, was revoked of his ability to possess firearms following his arrest in Washington. Illinois police also confiscated four firearms from his possession, including the AR-15 he used in Sunday's killing, a spokesman for the Nashville Police said.

Tazewell County Sheriff Robert Huston explained at a news conference that when sheriff deputies came to confiscate the killer's firearms last August, his father was present and asked the officers if he could take possession of the firearms instead. Tazewell said the father was legally able to possess weapons in the state of Illinois, so they turned the weapons over to him.

Authorities say the killer's father later returned the firearms to his son. However, it was not immediately known if there was a Tennessee law that prohibited the killer from possessing the firearms.