GRAND PRAIRIE, Texas -- For John Raidy's family, news of Tammy Lowe's arrest came as a relief.
"Then when we found out she was a teacher, it was disbelief," said Mike Raidy, John's great uncle.
Lowe, 53, a social studies teacher at Adams Middle School in Grand Prairie, surrendered to police on Tuesday ending a five-day mystery.
Police said she admitted to hitting and killing six-year-old John Raidy with her 2008 Toyota Yaris as the child walked home with his mother last Thursday.
After striking and killing the boy, witnesses said Lowe sped away. Surveillance video, police said, confirmed that she ran a red light following the incident.
"I guess you could say she actually was heartless," Mike Raidy added. "Somebody who teaches and works with kids, and to do this and not come forward sooner? It's unspeakable."
Tammy Lowe spent Tuesday night in jail unable to immediately post a $100,000 bond after police charged her with failure to stop and render aid.
Friends told WFAA that Lowe is a great person and a dedicated teacher. She stayed at school late last Thursday, one friend added, to work the admissions both at a basketball game to earn extra money.
Lowe, who taught 7th grade social studies, has been with Grand Prairie ISD since 1996. After resigning, she said she was going to seek psychiatric treatment, according to the arrest affidavit.
The district said Lowe was not in class last Friday after the collision. Neighbors told us they saw a lot of activity at her home on Saturday.
"They had a family gathering," Ashley Mitchell said. "A lot of cars were over there. I could barely get out of my driveway."
On Monday morning, Mrs. Lowe returned to class, but the district said she was exhibiting unusual behavior.
On Tuesday, she showed up again — but only briefly.
"She had a handwritten resignation letter she left on the principal's desk early this morning, then she left the campus," said Sam Buchmeyer, Grand Prairie ISD spokesman.
Hours later, Lowe surrendered to police.
Detectives served a search warrant on her home in South Grand Prairie and towed her 2008 black Toyota Yaris back to the police station to be reviewed for clues.
What remains unanswered — and hard for Raidy's family to digest — is why an experienced educator would run over a child, leave the scene, and then wait five days to come forward.
Though she admitted being involved in the deadly hit-and-run, Lowe would not answer questions from detectives, police said.
John Raidy's funeral is Wednesday afternoon.