BUFORD, Ga. -- A man accused of strangling a mother and her 2-year-old son to death had exhibited odd behavior several times in the months leading up to the deaths, according to police records.

Gwinnett County Police believe Brandon Williams choked 30-year-old Natalie Nation and her young son to death at a home on Tybee Drive in Buford Sunday night. Williams walked to a nearby gas station after the murders and was arrested, police said.

Police said that Williams isn’t being cooperative in the murder investigation and has refused to answer questions, so they have been unable to determine a motive.

PHOTOS | Mother, son dead after being choked by man

Brent Lenz, who said he has known Nation for years, said she had been living with Williams’ father.

Lenz said that Williams was exhibiting strange behavior over the weekend, including wearing a Halloween pumpkin-mask and threatening remarks.

“He came around to my side and said something about burning down the house,” Lenz said.

Williams has several previous incidents and arrests, according to Gwinnett County Sheriff’s Office records.

PHOTOS: Brandon Williams previous mug shots

Less than two weeks before the murders, police were dispatched to Tybee Drive after someone reported that Williams was walking around in people’s yards and aggravating people. Williams had reportedly been licking and looking into car windows and checking locks. Williams allegedly told one person that he wanted to knock out the window of a car and drive it.

Williams told the responding officer that he was outside “looking for signs of the universe,” according to the police report. Williams asked the officers if they were “6-pointed stars”, and said that the signs of the universe were “all aligned now”.

Officers determined that Williams was “not of sound mental status” and was taken into custody to be evaluated by mental professionals. While he was being taken into custody, Williams alleged resisted and officers used to a Taser to get him into handcuffs.

"There was evidence prior to today that he wasn’t with it, completely mentally, but nothing to indicate that he was capable of killing the mother and child," said Gwinnett County spokesperson Cpl. Michele Pihera.

About two months before that incident, on Feb. 7, 2017, Williams was arrested on violation of probation, and obstruction an officer. According to the incident report, a sheriff’s deputy arrived at his home and attempted to serve a search warrant. The deputy found the door of the home unlocked and opened it. From an upstairs room, Williams told the deputy that he was “not coming out,” according to the incident report. As backup arrived, Williams’ father arrived on the scene and authorities were able to take Williams into custody. He left jail on March 9.

On May 4, 2003, he was arrested on charges of fleeing/eluding police, reckless driving, speeding, starting a parked vehicle unsafely and possession of a weapon on school property.

On Dec. 13, 2013, he was charged with failure to appear.

On July 27, 2014, he was charged with DUI-alcohol and improper lane usage.

Williams now faces felony murder and aggravated assault charges and is being held without bond at the Gwinnett County Detention Center.