Credit Suisse's private investigator acted "defensively" in a physical altercation with former star banker Iqbal Khan, citing a report filed by the security firm. Khan is moving to rival bank UBS to be co-head of wealth management. Credit Suisse was reportedly worried he'd poach other employees, which led it to hire the security business Investigo to observe his actions, the new report found. The firm was asked to not break any laws or get too close to the banker. By Investigo's version of last week's events, one of its employees was conducting surveillance on Khan from his car when the banker approached him and shouted at the investigator. Khan tried to photograph the employee, who blocked the attempt. The investigator acted "defensively" against Khan, according to the firm's report. Khan noticed he was being tailed while driving with his wife last week, and photographed the following vehicle. The pursuit led to a physical confrontation in Zurich when the investigator attempted to take Khan's phone and the photos he took, people familiar with the events told Bloomberg. Khan served as CEO of the bank's International Wealth Management division, and has been on leave from Credit Suisse before starting his new role as UBS's co-head of wealth management on October 1. Three men were arrested after the pursuit, and an investigation into the events is ongoing. Credit Suisse announced Monday it started an investigation into the events.