Washington law determines how long after an event an individual can be charged with a crime. Snohomish County is no different. The rules are laid out in detail in section 9A.04.080 of the Revised Code of Washington. The Statute of Limitations only governs the time limit for filing of charges. Once charges are filed, the time for trial rules (also known as "speedy trial" rules) control how long the state has to bring an individual to trial. If charges are filed in a timely manner, and a valid warrant is issued before time for trial runs out, a case remains open forever. Time for filing is also tolled if the defendant fleas the state.
The rules for misdemeanors are simple. Charges designated as misdemeanors (90 days, $1000 max.) must be filed within one year of the date of the incident. Driving While License Suspended in the Third Degree, Hit and Run Unattended Vehicle and Criminal Trespassing in the Second Degree are probably the most common "simple misdemeanors." Gross misdemeanor charges (364 days, $5000 max.), such as DUI, Fourth Degree Assault and Theft in the Third Degree, must be filed within 2 years of the date of the crime.
The rules for Felonies are much more complex. The general rule is that a felony charge must be filed within 3 years after commission of the crime. However, the exceptions to this are numerous. Most crimes that result in death have no time limitations for filing. The statute of limitations for many sex crimes, violent crimes and theft crimes are 6-10 years from the time the crime is discovered. If the case involves child victims the SOL may not start running until the victim reaches a certain age. If you have been charged, or think you could be charged, you should contact an attorney to help you determine what rules apply and how best to proceed.
Waiting for a charge that has been filed to go away does not work. If you have a warrant you need to contact an attorney to get help quashing the warrant and proceeding with your case.
If charges are filed outside the Statute of Limitations the case must be dismissed. A defendant cannot waive this jurisdictional requirement.