A prominent Indian-American restauranteur, who helped convict a powerful local politician and exposed widespread corruption, has been sentenced to four years for bribing him.

Harendra Singh was handed the relatively lenient sentence on Wednesday by Federal Judge Joan Azrack who credited him for his cooperation with the government “possibly unmatched by any defendant in a corruption prosecution,” according to Newsday.

His testimony during the trial of Edward Mangano, the former head of the county government, “exposed the corrupt culture that was business as usual in Nassau County”, which adjoins New York City, the judge was quoted as saying.

News 12 Long Island TV said that the judge cited his cooperation in the trial of Mangano as a reason for imposing on Singh a lower sentence than prescribed.

The prosecution had asked for a sentence of 14 ½ to 17 years.

Singh, 64, who operated about a dozen restaurants and catering facilities, had admitted in court in 2016 to eight charges, including bribery, tax law violations and making a fake claim of $1 million, to a federal agency for damages he said one of his businesses suffered in a storm.

He had also asserted that he gave a bribe to former New York Mayor Bill de Blasio for a concessional city lease for a waterfront restaurant, but prosecutors did not charge the politician as they said there was no evidence that he personally benefitted from the money given to his campaign.

The allegation was one of the factors that helped end de Blasio’s run against President Joe Biden for the Democratic Party’s presidential nomination.

Another official whom Singh claimed to have bribed, John Venditto, the late head of the town of Oyster Bay, was put on trial but acquitted.

Mangano is serving a 12-year sentence for accepting from Singh bribes of money, a no-show job paying $100,000 per year for his wife, vacations, furniture and a home improvement project.

Mangano’s wife, Linda, was sentenced to 15 months.

The same day that Singh was sentenced, Fredrick Mei, a lawyer for Oyster Bay, was sentenced by the same judge to two years for taking bribes of $70,000, a car lease and vacations from him.

The bribery schemes centred on Singh’s bid to get a loan of $20 million by having the town of Oyster Bay guarantee it.

Arzac ordered Singh to pay $22 million in restitution.

He spent 15 months in a federal jail and about two-and-a-half years in home detention with an ankle monitor in the nearly seven years since admitting guilt, which amounted to a conviction.