Frederick Roosevelt Geeslin was born January 31, 1905, on a farm in Russelville, Ohio, the third of six children of John Titus Geeslin and Myrta Mae (Bourqin) Geeslin. He was graduated from Russelville High School in 1923 and attended Greenfield Business School in Greenfield, Ohio. He traveled west and on August 6, 1928, he became an assistant clerk with the Bureau of Indian Affairs at the South Pueblo Agency in Arizona. He was assigned to the San Carlos Agency in Arizona on September 1, 1932, and it was there he met a nurse, Jessie Brownjohn, whom he married in October, 1933. He returned to South Pueblo in 1934, and then was transferred to BIA offices in Albuquerque, New Mexico.

In 1937 he was transferred as a field aid to the Taholah Agency in Hoquiam, Washington. In 1939 he was named a chief clerk and stationed in Juneau, Alaska. During World War II he assisted in the relocation of Aleuts.

On January 1, 1948, Geeslin was transferred to Sitka to serve as assistant superintendent, and later, superintendent of the Alaska Native Service high school and medical facility on Japonski Island. The surplus buildings of the wartime Navy base on the island evolved into Mt. Edgecombe boarding school. Geeslin remained superintendent until July, 1955. He died at the age of 88 on July 6, 1993, at the Sitka Community Hospital.