O'Keeffe was also a former member of coach Ron Ballatore's UCLA Bruins swimming and diving team at the University of California, Los Angeles, before returning to Guam in 1995.

O'Keeffe made his official debut, as Guam's only swimmer, at the 2000 Summer Olympics in Sydney, where he competed in the men's 100 m butterfly.

[3] He challenged seven other swimmers on the second heat, including fellow two-time Olympians Conrad Francis of Sri Lanka and Nicholas Rees of the Bahamas.

O'Keeffe currently lives near St. Louis, Missouri where he is the coach of the Sunset Hills Stingrays summer swim team in Edwardsville, Illinois.

His sister Garland O'Keeffe, a former world ranked swimmer, was also a former head coach of the women's swimming team at the University of Iowa.