Adam Gautreau, 36, was one of four people shot and killed in a series of random shootings in North Texas over the last several weeks.
As of Sunday night, the man accused of killing multiple people across Dallas-Fort Worth over the course of several weeks, remained behind bars.
From there, investigators put the pieces together and said Harris was tied to several other crimes and has been charged with murder in two other cases, which increased his bond to $3 million.
'Definition of a Serial Killer'
Dallas police said he's the lead suspect in the random killing of an SMU student on Halloween in downtown Dallas along with two other fatal shootings and three aggravated shootings.
"In my opinion, based on what I've seen so far, I believe this is the definition of a serial killer," Dallas Police Deputy Chief Reuben Ramirez said, due to the random nature of the crimes which don't hold any apparent connections.
One of the fatal shootings ended the life of 36-year-old Adam Gautreau.
Dallas police said Gautreau was homeless and shot nine times near the intersection of Empire Central and N. Stemmons Freeway at about 8:30 p.m. on Sat., Nov. 14.
"I feel like I lost a son, I do, I'm heartbroken. I'm heartbroken," said Tiffany, the grandmother of Adam's 11-year-old son.
Tiffany, who asked NBC 5 not to publish her full name, said she's known Adam since he was 16.
They used to live in New Hampshire and he started to work for her husband who owned a roofing company 20 years ago.
"He was a great kid," Tiffany said. She said they took him under their wing.
Gautreau and Tiffany's daughter have a son together. Tiffany said they moved to Texas after her husband passed away and Adam followed three years ago to be closer to his son.
"Adam was a wonderful, wonderful person. Would never hurt a soul, and had a beautiful smile, great guy. He'll very much be missed by his family, and all his friends up in New Hampshire," said Tiffany, who said Gautreau's nickname was "Goat Rope."
Tiffany said the last year has been tough for Gautreau, who was homeless.
"His mom had passed away, his biological mom, from cancer, and that really depressed him," Tiffany said.
She said he turned to drugs and was living on the streets. Usually, Gautreau could be found in the same area of N. Stemmons Freeway, according to Tiffany. She said they tried to help him and check in on him.
"A lot of people think that a lot of people who are homeless and turned to drugs are all bad people, they're not. They're not. They're good people that just fell into hard times. They're still wonderful people and they still have families out there," Tiffany said.
She said they last saw Gautreau about three weeks ago when she cooked him a meal.
"He looked really good, he looked in good spirits and he was saying he was trying to get clean and change his life," Tiffany said.
But that opportunity never happened.
"It's disgusting. I just can't believe that somebody would just randomly go killing people," she said.
Video from a gas station across the street from where Gautreau was found shot to death shows a black SUV speeding away from the intersection after someone exited and then returned to the vehicle.
Tiffany said the family learned Gautreau had arrived at the corner of Empire Central and N. Stemmons Freeway about five minutes before the suspect arrived. A corner which usually was occupied by someone else who usually stood there.
"That poor man is going through a pretty traumatic time right now having nightmares, because he literally was like, 'Here, you can have this corner.' Adam was there like five minutes," Tiffany said.
She said despite their hardship, there is a sense of relief after police arrested Harris in connection to Gautreau's murder.
"I was at work and my other daughter [who] had been talking to the detective called me and was like, 'They caught him!' and I was like, 'Oh, thank God!' You know, I was just so happy. I was so, so, so happy because I really kind of felt like they're never going to find this guy, you know? They're never going to find him," Tiffany said. "So I'm very, very happy. I know he hasn't been fully charged and sentenced yet, but I feel like justice is going to be served for Adam and all the victims of this horrible person."
She said the family has rallied around Gautreau's son to support him as he grows up.
"He's OK. He's 11, so really hasn't grasped it yet, but he's never going to see his dad again. I think as holidays come and go and he gets older, he's going to realize that his dad is gone and he's never going see him again," Tiffany said. "Adam will be seeing my grandson grow up from heaven, because I know my grandson is going to be a great person when he gets older. It's just sad ... it's really sad that he's going to miss out on that."