At around 4:30 p.m. on Thursday, Visalia Police responded to the Visalia branch of the Tulare County Public Library and learned Nathan Valentino allegedly touched a girl inappropriately.
"When the incident occurred, the juvenile immediately contacted their parent, who in turn contacted security," said Visalia Police Sgt. Gary Williams. "And I believe security is the one who contacted us."
Police found Valentino inside the library and took him into custody.
As part of a statement, library officials said the safety of patrons and staff is a priority.
"The security guards and library staff acted quickly when the incident was reported and law enforcement was called immediately," they added. "We were grateful to the Visalia Police Department for their quick response and assistance."
Valentino has a long criminal history in Tulare County (dating back to 2010), including sex crime convictions.
Court records show prosecutors charged him with lewd acts on a girl under the age of 14 following an Exeter Police investigation.
In early 2017, Valentino was found incompetent to stand trial, and a few months later, he was sent to Atascadero State Hospital.
Later that year, he was restored to competency.
In January of 2018, a judge released him on his own recognizance.
But in March, prosecutors filed another sex case against him, after another, separate Exeter PD investigation.
A judge sentenced him on both cases last summer.
Valentino is being held at the Tulare County Pre-Trial Facility.