Geisel joined the Department in 1970, completing tours as management or administrative officer in Brussels, Oslo, Bern, and Bamako, and as Consul General in Durban, South Africa.

From 1986 to 1993, he served as management counselor at U.S. Embassies in Rome, Bonn, and Moscow.

He returned to the Department in 1993 as Executive Assistant to the Under Secretary of State for Management, where he supervised the creation of a worldwide process for allocating information technology resources.

He held the position of Deputy Assistant Secretary of State for Information Management, from 1995 to 1996, during which he was responsible for some 2,000 employees and directed the development of the Department's first IT strategic plan.

He returned abroad in 1996, serving as Ambassador to the Comoros, Mauritius and Seychelles until 1999, and as a senior negotiator, leading discussions with foreign governments on base access and defense cost burden-sharing from 1999 to 2000.