Ukiah man arrested after explicit online chats with undercover agent posing as child
San Mateo County, California – An undercover chat investigation in San Mateo County has led to the arrest of a registered s** offender from Ukiah, after authorities said he engaged in explicit online conversations with a person he believed was a 13-year-old boy.
According to the San Mateo County Sheriff’s Office, the case began in April 2026, when detectives with the San Mateo County Sheriff’s Office worked with the Silicon Valley Internet Crimes Against Children Task Force on an operation aimed at identifying people suspected of targeting minors online. The investigation was conducted through undercover chats, a method often used by law enforcement to detect and stop potential child exploitation before it moves further.
During the operation, investigators said 36-year-old Christopher G. Purtill of Ukiah communicated with an undercover agent in San Mateo County. The agent was posing as a 13-year-old boy. According to the Sheriff’s Office, the conversations became explicit.
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Authorities said Purtill is a convicted felon, a registered s** offender and was on active parole at the time. His parole stemmed from a prior conviction under PC 288 (a), which involves committing lewd or lascivious acts with a child under the age of 14.
The investigation moved from online evidence to an in-person arrest on May 7, 2026. Detectives with the San Mateo County Sheriff’s Office, working with the Ukiah Police Department and California corrections officials, contacted Purtill near his home in Ukiah. He was arrested for violating his parole conditions and booked into the Mendocino County Jail.
The case did not end there. After reviewing the evidence gathered during the undercover operation, investigators sought and obtained an arrest warrant on May 12, 2026, for alleged violations of PC 647.6 (c)(2) in San Mateo County. Purtill remains in custody in Mendocino County and is expected to be transported to San Mateo County at a later date.
The Sheriff’s Office said the investigation reflects its continued work with regional and state partners to identify individuals suspected of exploiting children online and bring cases forward through the criminal justice system.
Anyone with information related to this case is encouraged to contact the San Mateo County Sheriff’s Office Investigations Bureau at 650-599-1536. Anonymous tips may also be submitted by calling 1-800-547-2700.
