Prosecutors called Jack Rossiter to testify Monday about his 2006 interviews with the Rev. James Brennan. Brennan is on trial for the alleged 1996 sexual assault of a teenage boy.
Rossiter said he found the accuser credible, even though the man's criminal record gave him pause.
On cross-examination, Rossiter said the man's family had money problems when they came forward with the decade-old allegation about Brennan.
The accuser has also sued the archdiocese, along with Rossiter's private investigation firm and others.
Brennan is on trial with Monsignor William Lynn, the longtime secretary for clergy. Lynn is charged with child endangerment for allegedly covering up priest-abuse complaints.