A train operator advised that there was a subject who entered the bore at the south end of the 12th Station. Officers coordinated a search for the suspect via train and eventually saw that the train operator of a Daly City bound train was able to get him to board his train while still on the track way. The Daly City bound train was requested to hold at the Oakland West Station with doors closed. Upon the officers’ arrival, the train operator reported that the suspect walked to the last train car. The officers located the subject in question in the last train car. The officers who saw the suspect in the track way were unable to identify the suspect in question but the train operator was. The train operator placed the suspect under citizen’s arrest for interfering with railroad operations. A wants check revealed that the suspect had an outstanding misdemeanor warrant for his arrest for trespassing issued from the San Mateo County Sheriff’s office. The suspect was deemed a danger to himself and so was transported to for psychiatric evaluation. The suspect additionally had numerous previous contacts with this agency for 5150W&I and trespassing on railroad property. The suspect is to be booked for his warrant and for trespassing on railroad property once he is cleared. Trains were delayed for about 23 minutes as a result of this incident. TSOC was notified.