(Adds testimony of first witness)
By Kathy Finn
NEW ORLEANS, Jan 30 (Reuters) - Prosecutors accused former New Orleans mayor Ray Nagin, who led the city during Hurricane Katrina, of running a graft scheme that netted him cash, vacation trips and granite supplies in exchange for contracts to help rebuild the city after the storm.
Nagin, 57, who was swept into office on promises of good government in 2002 and re-elected in 2006, was indicted a year ago by a federal grand jury on 21 counts of corruption, including bribery, wire fraud, conspiracy, money laundering and filing false tax returns.
"The evidence presented at this trial will show that Ray Nagin was a corrupt mayor - plain and simple," prosecutor Matthew Coman said in a 45-minute opening statement on Thursday.
Nagin's attorney, Robert C. Jenkins, told the jury to expect ample evidence that will counter the prosecution's charges.
"We have thousands and thousands of emails that support that there was no corruption ... no kickbacks," Jenkins said in an opening statement that lasted about 10 minutes.
If convicted, Nagin could be sentenced to at least 20 years under federal guidelines, said Tania Tetlow, a Tulane University law professor and former assistant U.S. attorney.
Among other things, Nagin is accused of receiving kickbacks and free family trips to Hawaii and Jamaica in exchange for contracts for city business.
Prosecutors said a major contractor seeking business from the city gave the mayor $50,000 in payoffs and sent truckloads of granite worth an estimated $200,000 to supply a kitchen countertop company Nagin owned with his sons.
Nagin not only accepted bribes while in office, but also arranged for post-City Hall payments of more than $112,000 from contractors between August 2010 and March 2011, Coman said.
"In all, Ray Nagin took in more than $500,000 in illegal proceeds," Coman said.
During a long federal investigation, former Nagin aides and associates signed plea deals with the government, agreeing to testify against him.
Nagin's attorneys questioned the credibility of those witnesses, especially after they agreed to testify against the former mayor in exchange for a lighter sentence.
Rodney Williams, the former president of a company that sought city contracts from the Nagin administration after Katrina, was the first witness called, and he said Nagin's sons shook him down for money.
In 2007, while his company was awaiting action on a city contract, Williams said Nagin's two sons, Jeremy and Jarin, who co-owned the countertop company with their father, asked Williams to invest $60,000 in their company, Stone Age LLC.
"The mayor told me that he was tapped out and didn't have any additional funding to put into the company and would appreciate me (investing) the money his sons had requested," Williams testified.
Williams has pleaded guilty to bribing a public official.
Nagin was thrust into the national spotlight in 2005 when Katrina overwhelmed levees and flooded 80 percent of the city, killing 1,500 people and causing some $80 billion in damage.
Thousands of New Orleans residents, especially poor African-Americans, were displaced by the storm and many were relocated for months or left New Orleans permanently.
During the crisis, Nagin publicly clashed with federal and state officials over relief efforts and was accused of making inflammatory statements.
Later, Nagin, who is black, was criticized for racial divisiveness after he urged residents to rebuild a "chocolate New Orleans," referring to its majority African-American population. (Writing by Jon Herskovitz; Editing by Gunna Dickson and Mohammad Zargham)