Run somebody/something to earth/ground
Definition 1 of 1
Pro Tip 1/3Persistence Implied
The phrase suggests a long, persistent search before success. 
The journalist ran the story to earth after months of investigation.
Pro Tip 2/3Metaphorical Hunt
Metaphorically compares searching for someone or something to hunting. 
They ran the missing artifact to ground in an old warehouse.
Pro Tip 3/3Difficult Endeavor
The phrase often indicates a challenging task that requires effort. 
The team ran the software bug to ground after weeks of testing.