Detectives Seeking Additional Victims in Sex Abuse Case

Posted June 2, 2026

On May 16, 2026, Washington County Sheriff's Office (WCSO) detectives began investigating a sexual assault case involving 53-year-old Jacob Joaquin Mandes. Sr. Detectives with the Astoria Police Department reached out after getting information that Mandes admitted to a family member that he had sexually assaulted a child in Cornelius.

WCSO Violent Crimes Unit detectives developed probable cause to arrest Mandes for numerous crimes that occurred over the past 10 years. Working with Astoria Police, the Clatsop County Sheriff's Office, and the Columbia County Sheriff's Office, detectives had Mandes arrested the same day the report was made. On May 20, a Washington County grand jury then indicted Mandes for the following crimes:

• Rape in the first degree (2 counts)
• Sodomy in the first degree (2 counts)
• Sodomy in the second degree (2 counts)
• Unlawful sexual penetration in the second degree (2 counts)
• Sexual abuse in the second degree (11 counts)

A Washington County judge ordered Mandes held without the possibility of release while the case is pending. Additional charges are possible as the case continues.

Based on the investigation to date, detectives believe there may be additional victims. Mandes has lived or worked in Washington, Columbia, and Clatsop counties in the past. His address history includes Cornelius, Hillsboro, Astoria, and Vernonia.

If you would like to speak with detectives, please call 503-846-2500 and reference case 50-26-6744.

The release of Mades' booking photo is for law enforcement purposes and is in accordance with Oregon House Bill 3273 for the identification of additional criminal activity.

Contact