"We believe she might be able to help us with a current investigation."

"What can you tell me that might help with my investigation?"

It had to do with an investigation now going on.

"Says he might be able to help with the investigation."

And I will stay out of anything to do with the investigation, but this is a fine young man.

Perhaps that was the problem with the investigation so far.

And still others have left for private reasons having nothing to do with an investigation.

"They'd never let you near it with all the investigation going on."

"Are your friends going to help with the investigation, too?"

He'd made it clear that she was to have nothing to do with the investigation.