My great grandfather was Timothy Thadeus Killeen, born in Caranagary, Ireland in 1852. His father was Patrick Killeen. The information passed to me, unverified, was that Patrick's wife was Ellen Melone. We may have a match since I cannot confirm Ellen's last name. Do you have any more information on Ellen Sexton?
Timothy married Margaret Esther Ryan in PA in 1863. My grandmother, Hannah Gertrude Killeen is their daughter.