How to report a sexual offender?

What is the name of your state (only U.S. law)? WA

I have reason to believe that someone I know is an unregistered sex offender. This is someone with whom I must come into frequent contact. This person is under an alias from another state, where this person has spent time in prison for rape, assault, and sexual crimes against a minor. I know the alias, the charges spent time in prison for, and which state this was. This person has two sexual harassment charges already at work and is becoming sexually aggressive to at least two people that I know of. How do I go about reporting this person to the proper authorities here in Washington?

Did you consider speaking to your local police? That would seem like a logical place to start.

I wasn't sure if I should speak to local, as I live in another town, the county, or state? There were websites I could find to report this for other states, but I could find nothing here in WA.

Speak to your local police and they will refer you if necessary.

If for some reason they try to blow you off then try a county law enforcement agency (sheriff?) if it exists.

Sheriff. Thanks. Local law is small town and small minded, but sometimes they actually try to help. Will start with them.