"Gary was always cool with us," said Devan Putman, 15.
She’s been a member of the church’s youth group for as long as Welch was its leader.
"[He was] always giving us hugs and high-fiving us," she said. "I just couldn’t believe it."
Late Monday afternoon, Corsicana police officers arrested Welch, 42, at the church on charges of aggravated sexual assault of a child. He remains in jail on a $150,000 bond.
Police would not clarify if the girl was a member of the church, but said they are investigating whether there could be more alleged victims.
"We just want to be diligent," said Corsicana Police Chief Randy Bratton. "Right now, we don’t have any indication there are additional victims."
Court documents say a 16-year-old girl came forward to police on Saturday after she confided to her aunt she had been sexually assaulted by Welch for more than two years - since she was 13 years old. Court documents say the abuse "happened numerous times at several different locations" and that the two last had intercourse on New Year’s Eve.
Two days later, Jan. 2, Welch wrote about sin and evil on his Facebook page. He referenced a Bible verse, Romans 6:13, about not letting "any part of your body become an instrument of evil to serve sin."
Welch posted, "In sin, every part of our bodies is vulnerable. In Christ, every part can be an instrument for service."
Toby Thornton said he had his suspicions about Welch three years ago, when he realized the youth minister was showing interest in his teenage stepdaughter.
"This guy was texting our daughter at all hours of the day and night," he said. "He was going to school, eating with her at lunchtime... Seems like it exceeded the scope of a youth minister."
Thornton says he never saw anything sexual, but pulled his stepdaughter out of the church and complained to the pastor, Rick Lamb.
"It kind of fell on deaf ears," he said. "He kind of blew our concerns off and said that [Welch] was a very kind and loving man.”
He said officers interviewed his stepdaughter the morning after the arrest.
Lamb declined to speak with News 8. He released a statement, saying the church was "shocked and deeply saddened to learn of the arrest."
Northside is one of the largest churches in Corsicana. Every Sunday, hundreds fill its soaring sanctuary.
Welch joined the church in 2005 and lived steps away with his wife and two sons. His online biography says he grew up in the West Texas town of Munday, where his mother was the church secretary. After moving to North Texas as a teenager, he ministered at churches in Forreston, Palmer and Ennis. His bio says he was attending Navarro Junior College and hoped to eventually get a Masters in religion.
His family in Corsicana declined to speak with News 8.
Neighbors say despite his prominent role in the community, the minister didn’t mingle with the people living on his street.
"He was a real quiet man - really quiet," said neighbor Joe Reed.
The neighborhood is the kind where many leave their front door open during the day.
"It’s a very big betrayal," said neighbor Jeanie Burkholder. "The kids are all taught to look up to a man like him... It’s hard to respect anyone like that."