The Bronx district attorney has found no cause for a criminal proceeding against Msgr. Charles M. Kavanagh, the most prominent New York priest caught up in the Catholic Church's sexual abuse scandal. Now, according to the New York Archdiocese's policy, a special review board is expected to take up his case next week to determine whether the monsignor can return to ministry.The Bronx district attorney, Robert T. Johnson, found the Kavanagh case and a number of others to be beyond the statute of limitations, his spokesman said this week.Church officials are struggling to find the truth in the case, which they say is the most difficult facing Cardinal Edward M. Egan. Until now, it has generated little but frustration for Monsignor Kavanagh's accuser, Daniel Donohue, and the popular clergyman's many supporters. It is just one example of how the abuse cases involving priests around the country remain unsettled despite intense efforts by American bishops and the Vatican to deal with them and the resulting public outrage.