By Tony Romeo

HARRISBURG, Pa. (CBS) — A once-powerful Pennsylvania House speaker was found guilty today of corruption and related charges.

William DeWeese was Democratic leader of the state House when he was accused of using public resources, mainly staff, for campaign purposes (see previous stories).   He is still a sitting member of the House.

This morning, a jury in Harrisburg found him guilty of three of four counts of theft and one count of conspiracy, relating to allegations that he required taxpayer-paid staff members to work on his election campaigns as part of their jobs.

A female in the courtroom, apparently a supporter of DeWeese, cried aloud as the verdict was read.

DeWeese’s lawyer vowed to appeal the verdict, and a defiant DeWeese said afterward that he would seek re-election.

“I believe that in the court of public opinion, I shall be favorably received to some substantial degree,” he told reporters.  “That’s up to the voters. But I will certainly continue to run for renomination and re-election.”

He quipped that he is volunteering to help escort Gov. Corbett to the podium for his next budget address.

But prosecutor Ken Brown thinks the verdict will send a different message:

“The jury clearly listened to the Commonwealth’s evidence, and they found the defendant to be what the Commonwealth said he was from the moment these charges were filed: that he’s common criminal,” Brown said.

DeWeese would be required to give up his House seat upon sentencing.

The former Democratic House leader was one of the last to be charged among the 25 people connected to the House Democratic and Republican caucuses who were arrested in a five-year-old state corruption investigation begun by then-attorney general (now governor) Tom Corbett.

Brown, the prosecutor, says sentencing guidelines suggest a minimum of nine to 16 months in prison for each guilty count.

DeWeese had been a member of House Democratic leadership for two decades.  The 61-year-old Greene County lawmaker was the only sitting legislator to go to trial.