undercover operation

It was intended that the undercover operation last for around six months.

Soon after, other family members involved in the undercover operation are killed.

For now, an agent was killed during an undercover operation.

Do I know how to conduct an undercover operation, or what?

And for undercover operations to take place to enforce that law.

The names of the drug agents in the undercover operation were not made public.

Your magazine calls it "one of the most successful undercover operations in history."

The man was not involved in the earlier undercover operation, the police said.

The stage was set for what would become an 18-month undercover operation.

She is said to be in a deep undercover operation.