Lyle Newson heard the gunshots, but thought little of what his neighbor might be doing across their common wall as he and his girlfriend got ready for a Christmas party Saturday.

When they opened the front door, Justin Hess, their 31-year-old neighbor, was walking up the doorstep and speaking in a fake British accent, Newson said.

“I could see he had a gun, maybe a Glock, on his hip,” Newson said.

Hess had allegedly just shot his 61-year-old mother, Carol Ann Hess, to death in the east Cobb County townhouse they shared on Bridle Path, Cobb County police spokesman Sgt. Dana Pierce said.

After making strange threats directed at Newson’s girlfriend, Hess creeped away in his mother’s Mazda, inching slowly out of the neighborhood without headlights, Newson said.

That’s when Newson called Carol’s cellphone and Justin answered.

“He was talking in that crazy voice, saying, ‘Carol’s had a bit of a fall,’” Newson said.

The couple told detectives everything they knew and spent the night with family in Roswell before returning home Sunday morning to get some clothes.

Hess then drove to a Sandy Springs storage facility where he stabbed E. Rivers Elementary music and drama teacher William Haynes, police spokesman Capt. Mike Lindstrom said.

Haynes’ body was found hours later on the floor of Extra Space Storage in the 6700 block of Roswell Road. The 53-year-old had multiple stab wounds.

After stabbing Haynes, Lindstrom said Hess stole the man’s red Audi and returned to east Cobb.

Newson watched through his window as that same red Audi pulled into the driveway where Hess lived.

Moments later, police and SWAT officials surrounded the area and Newson and his girlfriend has to wait for an extraction team to get them safely out of their house, Newson said.

A brief standoff ensued before Hess walked out of his basement apartment peacefully and was arrested.

During his first court appearance Monday morning, Hess spoke with an accent and thanked the judge, Channel 2 Action News reported.

"Appreciate your service," Justin Hess, 31, told the judge.

The statement came moments after the judge decided not to set bond in the case, Channel 2 reported.

Hess remains at the Cobb County Adult Detention Center on felony murder and aggravated assault charges. He is expected back in court in January.

RELATED: Cobb County police arrest man accused of shooting mother to death

Haynes, the man stabbed to death in Sandy Springs, came to E. Rivers Elementary 16 months ago from Fulton County Schools. He was a director of The Alpharetta City Band, an adult community band, too.

"If somebody had said give me your car keys, he would've given them the car keys,” band program supervisor Don Nahser told Channel 2. "He would go out of his way to help you."

Haynes and Flowery Branch Mayor Mike Miller were friends.

"I read and hear everyday about senseless violence, but it is overwhelming when it hits home and someone you knew and considered a friend is involved,” Miller said in a Facebook post.

“R.I.P. Bill. I will see you again one day in heaven, but the euphonium section up there is sounding a little better today."

The man appeared in court and thanked the judge for his service.