After Mrs. Ryan's death in 1917, Ryan divided up the estate and in 1921 sold the main mansion to Edward Swann, New York City District Attorney. Several months later, Swann sold the property to the Archdiocese of New York, which used the mansion as a retreat site for St. Joseph's College and Seminary. In 1944, Suffern resident Gustav Mayer purchased the mansion. However, his plans to develop the property, including possibly as a country club, never materialized, and the vacant mansion fell victim to vandals. Copper mining giant Phelps Dodge Corporation bought the dilapidated mansion in 1951 and used it as their corporate records headquarters for the next 31 years. After Phelps Dodge relocated, it sold the mansion for $1.6 million to Gary M. Goldberg. CEO of the investment/financial planning firm which bears his name. After a year of extensive renovation, Montebello became that financial firm's headquarters as well as an office park.