Prosecutors have used taped evidence to build many successful cases against mob bosses, crooked cops and suburban mayors.
When FBI operatives implanted the Blagojevich bugs, they had the same aim: catch him in the act.
When federal officers removed box loads of physical evidence from rod Blagojevich's campaign headquarters, they might not have been carrying the most damning evidence against him, according to investigators. Blagojevich's own spoken words, they expect, will be. Conversations that the governor, inside his own home on the North Side. Phone conversations that occurred the past six weeks.
How did the FBI do it?
Nobody broke into the governor's house to install a phone tap like this one on his line, the way spies might have been accomplished it 25 years ago.
These days, federal agents can intercept calls electronically, from phone company switching centers but not without approval from the office of enforcement operations here at the Justice Department in Washington.
"Once it's been signed off at main justice which means you're allowed to do see it, you're still nowhere because you can't put in a bug or wiretap in without approval from the chief judge in the district so the chief judge takes an independent review and signs off on it," said Patrick Fitzgerald, U.S. Attorney.
In Blagojevich's case, Chief Judge James Holderman signed the intercept order which was sealed along with the governor's arrest warrant and other paperwork filed on Sunday.
According to this record of U.S. Intercept orders, more than 2200 wiretap requests were made last year, but most by state authorities and most in drug cases with only a handful for corruption cases such as the governors.
Chicago judge Holderman also approved the installation of a bug inside the Blagojevich campaign headquarters which did require federal agents to actually get inside the office.
Law enforcement sources also say there was also a secret camera installed in or near the Blagojevich office so that authorities could determine who was actually doing the talking.
That was the case with Chicago's most famous hidden law enforcement camera in 1989.
Federal agents had put a camera under a cushion inside counselor's row restaurant near city hall that shot out of the sidewall and was aimed at booth one, where aldermen, city officials and outfit bosses discussed the days rackets.
There was a microphone hidden in booth one and a tap on the telephone but the camera was used to record who was conducting criminal business.
Counselor's row is long out of business. But the business of corruption in Illinois has seen no recession.
Since Rod Blagojevich was an assistant cook county prosecutor 25 years ago, he has watched hundreds of friends, colleagues and acquaintances prosecuted for selling out their public positions. Many were caught on tape. Tonight, in their rogues gallery hangs a new portrait.