The diocese acknowledges Dempsey is under federal investigation for violating child porn laws.
Dempsey's parishioners at Our Lady Queen of Martyrs in Forest Hills were notified last weekend.
"You are undoubtedly aware of the deep suffering and hurt that surround any matter of child abuse, especially when allegations involve a member of the clergy. It can damage, often irreparably, the innocence, the trust and the reputations of all who are in any way affected by it." Bishop DiMarzio said in a letter read to parishioners.
The Diocese says it removed the monsignor immediately after learning of the investigation.
"The steps we have taken are essential to maintaining our commitment" to the bishops' Charter and Norms, the Bishop said. "It is a responsibility we take seriously." Monsignor Dempsey has served as the Executive Director of Pastoral Communications since 1978.