Updated 03/28/12 – 9:29 p.m.

CHICAGO (CBS) — The man who was Rod Blagojevich’s chief of staff when the former governor was arrested for trying to sell a U.S. Senate seat has been sentenced to 10 days in jail for his role in Blagojevich’s corruption case.

READ MORE: Galewood Man Charged With Aggravated Battery In The Stabbing Of CTA Bus Driver

John Harris was the star witness for the prosecution at the two trials that resulted in Blagojevich’s conviction on 18 corruption counts and 14-year prison sentence.

He had pleaded guilty in 2010 to conspiracy to commit bribery and faced up to five years behind bars. He had been seeking probation, but was given a sentence of 10 days in jail, two years of supervised release and a $1,000 fine at his sentencing hearing Wednesday afternoon.

LISTEN: WBBM Newsradio’s Lisa Fielding Reports

Harris, 50, began cooperating with federal prosecutors within days of his arrest and agreed to testify against Blagojevich, providing the bulk of the testimony against the former governor. Harris was sentenced less than two weeks after Blagojevich began serving his prison term.

U.S. District Judge James Zagel praised Harris for his cooperation with investigators and said that he sympathized with Harris having to deal with such a difficult boss as Blagojevich. But while heaping praise on Harris, the judge said that some, but minimal, time behind bars was necessary.

“The offense is so serious and so crucial that I cannot impose upon you a sentence that does not involve custody,” Zagel said.

Zagel spoke at length about Blagojevich and his working habits and how he wore down his staff. Zagel even said that if he were in Harris’ shoes he may have acted the same way.

READ MORE: 2 Men Shot In River North

“But I would have left sooner, much sooner,” Zagel said.

Before going to prison, Blagojevich claimed his motives were pure, but Harris was the first major figure to cooperate with the government — agreeing to do so three days after his arrest on the same day as Blagojevich in December 2008 — and told a much different story.

Harris admitted trying to help Blagojevich win appointment as U.S. Health and Human Services secretary or to find work heading a non-profit.

In a pre-sentence filing, attorney Terry Ekl argued that Harris warned Blagojevich not to attempt to sell President Barack Obama’s Senate seat, advising against several different scenarios, and ignored instructions from Blagojevich to shake down or threaten the Chicago Tribune or to withhold state business from banks that failed to assist Patti Blagojevich in finding work.

In a pre-sentencing filing submitted earlier this month Ekl argued Harris should be sentenced to unsupervised probation in light of his guilty plea and cooperation with the feds.

“Mr. Harris has acknowledged his full and complete responsibility for his conduct through his guilty plea, his execution of the plea agreement and, most importantly, his truthful testimony before this Court during the two trials of Defendant Rod Blagojevich,” Ekl wrote.

More than 40 current or former public officials had written Judge Zagel to attest to Harris’ character.

Harris resigned his post within days of his arrest and voluntarily gave up his law license shortly thereafter. Ekl said in his pre-sentencing filing that Harris has worked as an apprentice electrician’s helper, working on high-tension lines, to try to keep his family’s bills paid.

MORE NEWS: Teammates Of Boy Killed In Waukesha Christmas Parade Tragedy Honor Him With Baseball Memorial

(TM and © Copyright 2012 CBS Radio Inc. and its relevant subsidiaries. CBS Radio and EYE Logo TM and Copyright 2012 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. The Associated Press contributed to this report.)