There are two types of report, one is 報案. The other is 報失. For 報案, police needs to conduct investigation and your friend need to give statment. 報失 is only report lost and get a receipt as evidence. I suggest your friend to report to the police so that the police will have a record. In my case, the police found my lost ID with photo replaced was used by a 黑工 for very long time. I am glad that I have reported to the police so that the police trusted that I was not involved in the illegal activity and sold my own ID for profit.
報失 as the police don't want it do and treat it as 報案. Even my handbag was cut by cutter, he said if i was not seeing someone stolen my wallet directly, he could only accept me to report lost.