The eccentric older brother of Philadelphia’s last mayor was convicted of three tax-evasion charges Friday but acquitted of four fraud counts over what prosecutors had described as a kickback scheme at the city-owned airport.

The jury, which deliberated over nearly three days, deadlocked on two other tax-related counts against T. Milton Street Sr.

Street, 68, had pleaded not guilty to all nine charges in an indictment that said he took advantage of his relationship with then-Mayor John F. Street to make $30,000 a month as a consultant and minority subcontractor at the airport from 2001 to 2004.

Prosecutors alleged he did little or no work, and failed to report $2 million in consulting fees for tax purposes.

John Street left office last month after two terms as mayor, a tenure marred by an unrelated FBI investigation of the city’s pay-to-play culture. The FBI bugged John Street’s office but he was never charged; his city treasurer, two bank executives and others went to prison.

Milton Street testified that he did nothing illegal, telling the jury that he believes the U.S. tax code is unconstitutional.

The jury convicted him of tax evasion for not filing tax returns for 2002, 2003 and 2004. It deadlocked on two counts that accused him of underreporting his income for 2000 and 2001.

The counts on which he was acquitted all related to the airport contracts.

Milton Street last year ran for an at-large seat for City Council despite the indictment, questions about his residency and the fact his nephew was also in the race. He lost.

Street also has been a hot-dog vendor, a state senator and longtime political activist. He started an amphibious duck-boat tour operation that ended up in a court battle over turf with an established tour company.

Last year, he was arrested for allegedly racking up thousands in unpaid traffic fines in New Jersey, where he lives at least part time.