"I mean, it was just horrendous and he was clearly grooming," said Todd Thomas.
But when the Clovis dad allegedly caught a man sending his teenage daughter sexually explicit messages, he took matters into his own hands.
He made a citizen's arrest, and despite his instincts, he did it without violence.
WATCH: Video of Fresno County father making citizen's arrest
"The whole world will see you," a friend said in video of the arrest. "The whole world will see you."
Hugo Rabson's identity has been made public. An angry dad made sure of it.
Todd Thomas met Rabson in March 2017 after finding his 14-year-old daughter sleeping with contraband.
"She was laying there with her head on her arm and a cellphone in her hand and I don't let her have a cell phone," Thomas said.
He and his wife investigated to figure out how she got it and how she used it.
Their daughter told them she met Rabson, a 42, on an app called Whisper that she could access without her own phone.
Rabson eventually gave her the phone inside a hollowed out-book she kept to hide the phone at home. And he allegedly used it to send her messages.
"I was shocked at what I found," Thomas said. "The messages this man had sent to my daughter are worse than anything I'd say to a one-night stand."
KFSN reviewed an arrest warrant that apparently reveals the content of some of those messages.
"Daddy needs to see his little girl... naked," the suspect allegedly wrote, using the nickname he wanted to be called, "Daddy Sugar."
Thomas said his first instinct was to beat the man with a baseball bat.
"I wanted him gone, off the face of the earth," he said. "I couldn't believe he'd done this to my baby."
But Thomas knew violence wouldn't help anyone, so he hatched a new plan. He said he posed as his daughter and texted the man on the other end of the line, asking him to meet at the same place where the girl received the phone.
"The guy was sitting alone at this table, facing the dirt road," Thomas said.
The angry father brought a friend to help him make a citizen's arrest, and they recorded some of the interaction with Rabson. They recently posted the video to Facebook and users have shared it more than 1,500 times.
Clovis Police and Fresno County Sheriff's Deputies arrested Rabson. But in the search warrant, they state that Rabson reset his phone, deleting all evidence from the device. Investigators said they retained evidence on the phone he gave the girl.
Prosecutors charged him with felony arranging a meeting with a minor for lewd or lascivious behavior.
He pleaded not guilty last week and was released on a $30,000 bond.
When KFSN attempted to interview the suspect, a young man at his house told a reporter that Rabson wasn't home and couldn't be reached.
His attorney told KFSN that he's waiting to see the evidence before planning a defense.
Thomas says he wants to use his pain to help other fathers in similar situations.
"All over the world we have children getting attacked and dads having to deal with this," he said. "And if a dad doesn't get help, that family could end up without a father because he's going to off himself or go after that predator."
He said he was looking for counselors and anyone else who would help him create a support group called "Fathership."