What to do with money that someone found?

Posting on behalf of an enquiry I received.

A person found c.£5k in his shop (which is a local mobile phone repairs type store). He has held the money for 16 months and nobody has since been back. He checked the CCTV and thinks he knows who it was but that person has never been back.

He does not know who that person is but made efforts to identify the person by asking people locally. He received mixed responses: one respondent mentioned that the person had passed away, another mentioned he’d moved away.

What is the ruling for such money? Is he obliged to take any further steps?

Wasalam

May Allah bless you.
In this scenario, since he has more or less identify the person, can he check if the person has truly passed away and if the person has legal heirs? If he does, then he should pass on the money to them as they will be the rightful owner of the money.
If he is unable to locate anyone at all then he can keep the money for himself according to my teacher. Otherwise he can give it to charity. In both scenarios, if the owner turns up later on, then the money must be returned to him.
Another solution would be that to just wait until the owner turns up to collect the money.

And Allah knows best!