Police are hunting a thief who made off with a San Francisco Conservatory student's $23,000 violin. The student had left the instrument, a Caressa & Français from the early 1900s, in a Conservatory practice room while she checked her emails in the computer lab. A light-haired man apparently walked in and took the violin and the student's mobile phone. Another student followed the man and saw him get on one of the city's light-rail Muni trains. Police later released Muni surveillance video footage of the suspect.