To turn up something means to discover it.
If you turn something up or if it turns up, you find,
discover, or notice it.
Investigations have never turned up any
Turn up (Collins Dictionary)
In British English, 'turn up' with a direct object is used figuratively to mean 'produce, discover, or find' during an examination, search or investigation. Used literally, it means to bring something to the surface while digging in the soil. A detective might turn up some new facts while checking evidence in a case; a farmer might turn up buried treasure while digging in a field (while 'turning' or 'turning over' the soil).