A Lowell man already on the state’s Sex Offender Registry has been sent to prison for four years after acknowledging that the state has enough evidence to convict him of molesting a 5-year-old girl. Leonard Zaccagnini was sentenced Wednesday after entering an Alford plea to charges that include indecent assault and battery on a child. The plea means that while he maintains his innocence, he agrees that prosecutors have enough evidence to convict him. The Sun reported that, in addition to the prison sentence, a judge placed the 65-year-old Zaccagnini on probation for two years. A charge of indecent assault and battery on a child was dropped.