Dennis Crosby attended Bellarmine College Preparatory in San Jose with his other brothers where he graduated in 1952 and subsequently enrolled at Washington State University at Pullman on an animal husbandry course with his twin brother. He dropped out of the course after two years and was inducted into the Army in January 1955. He was initially posted to Fort Ord, California and then transferred to Fort Riley in Kansas for training with the US 10th Infantry Division which transferred for duty in West Germanyin the summer of 1955. When he was 21 in 1955, Dennis inherited $200,000 from his late mother's trust. In the late 1950s, Dennis and his brothers, Gary, Lindsay and Phillip, often performed as the Crosby Brothers in nightclubs and on The Ed Sullivan Show, though Dennis reputedly wished to avoid such appearances. On May 4, 1958, Crosby married Pat Sheehan, a Las Vegas showgirl and model who had once dated his father shortly after his mother had died. She was also Miss San Francisco of 1950, Playmate of the month of October 1958, and part-time actress. Within days, Crosby was sued by another woman, Marilyn Miller Scott, over the paternity of her daughter, Denise Crosby. The sensational lawsuit lasted three years and ended with Dennis being ordered to pay Scott child support and legal fees. This and the marriage to Sheehan and other details caused deep embarrassment for both him and his father. Although Bing Crosby died when his granddaughter was 19, the two reportedly never met. Crosby and Sheehan had three sons: Gregory Evan, Dennis Michael Jr., and Patrick Anthony. In 1963, while working in Los Angeles for Bing Crosby Productions, he met Arleen Newman. On July 3, 1964, Crosby and Sheehan were divorced. Later that year, Crosby married Newman, with whom he had three daughters, including Kelly Lee Crosby and Erin Colleen Crosby. Additionally, Crosby adopted Newman's daughter, Catherine Denise Crosby, from her first marriage to Mike Buell, which ended in divorce. Crosby and Newman divorced in 1991. On December 11, 1989, Crosby's younger brother Lindsay committed suicide by gunshot.
Death
Deeply distraught by his brother Lindsay's suicide and his own recent divorce, Crosby died from a self-inflicted gunshot on May 4, 1991, in Novato, California, aged 56. On January 14, 2006, Crosby's former wife, Pat Sheehan, died at the age of 74. Their son Dennis Michael Crosby Jr. died on January 15, 2010, and Patrick Anthony Crosby, died at Cedars-Sinai Medical Center in Los Angeles, on September 19, 2011, after a lengthy illness.