How to use "investigate" in a sentence

Polly Nichols was not the first 'Unfortunate' who was murdered that year, so Scotland Yard chiefs sent their most experienced officer to investigate

Maybe this would be the only opportunity to investigate.

Promise me we'll investigate this more closely when you come out."

"So if he tells them about that, they will investigate

But first I'm going to investigate that telephone call.'

'I must investigate this,' said the inspector