In many cases, the officials said, investigators from Internal Affairs field units monitored an officer for a long period, compiling a chronicle of minor infractions.

Lieutenant Biegel said investigators also monitored the Internet for the same purpose.

Mr. Brown also said that with the cooperation of other police departments, investigators would monitor officers outside their precinct boundaries, even following them to their hometowns.

He said in interviews that private investigators have monitored him, dug through his garbage, and followed him as he took his children to school.

He said his investigators would also closely monitor expenditures on the government-issued credit cards of Department of Homeland Security contracting officials involved in the hurricane relief program.

The Mont Blanc inquiry has wound down, although investigators are still monitoring the communications of a few people.

More recently, most investigators monitor cerebral perfusion using mean flow velocity recording with transcranial Doppler ultrasound in supine horizontal position, during and after head-up tilt.

A high-ranking police official testifying in that case mentioned that investigators had monitored 100 Blacks in Law Enforcement in connection with an investigation of Lieutenant Adams.

In December, investigators knew Dr. Lee was going to Taiwan for three weeks, but did not monitor him.

According to Christie, investigators monitored 17,000 phone calls during the two-year period before the March, 2010 raid.