@hachimaaan If this was 1980s based I'd agree. However... we live in dangerous times, where the heavens are always watching. (More like spying and suppressing)
Just the amount of security cameras around, not even counting smartphone footage, satellites, drones, and scary-ass flying listening/recording mosquito sized drones (not really used on public streets lol).
Even if in that exact spot there wasn't a camera if you look in either direction, on the main road say that regular people take, you'd probably find him in footage. Next it's just facial recognition software or the old fashioned method of hard work. I think he was wearing his school uniform. Even if he wasn't, based on height you can approximate age & assume he's a student.
You have enough influence you can have people comb through every student on file for every nearby school starting from the closest to the incident, further on until you find him. Even if your wrong about him being a student, can even go door to door around that area asking if they recognize him. (Probably just used facial recognition & security footage).
@7Lotus His point was, she didn't know him. You can't just say 'do a background check'. You need actual information for that, name helps immensely. Best if you happen to have their ID number.