A train operator reported a female had walked across the track way in front of his train to get to the other platform. Upon arrival, an officer detained the subject who was positively identified by the train operator. A warrant check revealed the suspect had an outstanding $10,000 arrest warrant out of Sonoma County for contempt of court. The train operator refused to place the suspect under citizen’s arrest for trespassing, and the suspect was placed under arrest for the warrant. TSOC notified. Trains were delayed for a few minutes.