Sometimes, he said, the medical investigators learned key information through news reports.
But in recent weeks investigators learned that did not occur.
It was not clear what investigators learned from the surveillance.
In the red envelope, there would be a question about what the investigators had learned during the day.
By checking bank records, investigators could learn where any particular person had been at a given time.
He declined to comment on what his investigators had learned.
They can be charged, however, for illegal activities that investigators learn about on their own or through others.
In that way, investigators could learn whether these women respond differently to treatment.
When investigators learned she was missing, they immediately searched the house.
Here are some of the things investigators can learn from bomb fragments.