A Marietta man charged with killing his mother over the weekend remains in the Cobb County jail after his first appearance hearing Monday.

No bond was set for Mario Nathaniel Dorce, 23, during the hearing. Dorce has been charged with fatally shooting his mother, 52-year-old May Carole Whitty, according to police.

Officers responded to the scene at the victim's home, located in the 2600 block of Tritt Springs Trace, at about 9 a.m. Saturday, police said.

Whitty's body was found inside the home with "obvious signs of trauma," police said in a press release.

Neighbors told Channel 2 Action News that the suspect was acting unusual Friday and Saturday.

Friday night, Dorce asked a neighbor if he could spend the night at their home.

“We said ‘We don’t really know you. We would prefer that you went to a neighbor that knew you a little better, maybe they’d be able to help you out,’” neighbor Shaun Simms said.

While under arrest Saturday, the “suspect was back in the cop car laughing, smiling, joking, um, singing songs and just acting a little crazy,” Simms said.

Dorce graduated from  Campbell High School in Smyrna in 2005, according to his Facebook page. He served in the Navy from June 2005 to April 2010, but Navy personnel would not release the location where Dorce was stationed or information about his departure from the military.

May Whitty had been a bus driver for Cobb County Schools since 2002, according to a school system spokesman.

"She was the sweetest woman," said neighbor Lisa McDonough, whose daughter rode on Whitty's bus. "She always greeted you with a smile, and chatted with parents. I was looking forward to seeing her again this year."

Whitty's death was a devastating loss for Rebecca Mitchell, whose older children rode Whitty's bus.

"My youngest child is starting kindergarten and all he has talked about is riding Ms. May's bus,"  said Mitchell, while on vacation in Florida. "I literally don't know what to tell my kids."

Whitty was from Haiti, Mitchell said, and the two women bonded after the earthquake hit the country last year while Whitty awaited word from missing family members.

"I'm not a very trusting person, but I trusted her completely," Mitchell said. "I considered her a friend."

Staff writer Janel Davis contributed to this report