A second son of reputed former Mafia chief Joseph Bonanno Sr. was sentenced to four years in state prison in a home improvement scam after a plea bargain. Joseph Bonanno Jr., 42, pleaded no contest in Alameda County Superior Court to conspiracy to commit grand theft for charging senior citizens for bogus repair work. Judge Joseph Karesh stayed the sentence pending an appeal of Bonanno's federal conviction and four-year sentence on fraud charges in an unrelated investment scam. Under the arrangement between Deputy Atty. Gen. Derald Granberg and defense attorney Colleen Butler, Bonanno can withdraw his plea if his federal sentence is reduced to two years or less. Butler said the plea bargain was an "unbelievably attractive" offer. Joseph's brother, Salvatore (Bill) Bonanno, 54, was convicted of conspiracy and grand theft in 1985.