She said that subpoenas were not issued at the outset because the expectation was that witnesses would cooperate.

He is expected to file motions in court as early as Tuesday to compel witnesses to cooperate.

According to federal officials, the witness had been cooperating with authorities a few days prior to the T.I. arrest.

State prosecutors lack a comparable program to encourage witnesses to cooperate.

That witness, Mitchell Diaz, 22, is cooperating with the government as part of a plea bargain.

Owing to intimidation, witnesses would not cooperate with the police.

Such visits are a standard technique used by law enforcement officials when they suspect a witness might cooperate if approached outside the office.

"Unfortunately, our criminal-justice system requires that the complaining witnesses cooperate with the investigation," he said.

When an important witness will not cooperate, nothing can be done.

But the first Palestinian witnesses did not cooperate.