At the time of Griffith's Valuation Baron de Heizler held three townlands in the parish of Annagh, barony of Costello, county Mayo, formerly the property of C. Higgins. The Baron was married to Mary Jane Higgins. In 1878 the Baron with an address at Mount Brown, Dublin, held 243 acres in county Mayo and 575 acres in the county Laois (Queen's county).
National Archives of Ireland:
Landed Estates’ Court Rentals (O’Brien), Peel and de Haeseler, 30 May 1876, Vol 123, MRGS 39/056, (microfilm copy in NUIG)