Career
Competing for West Germany, Keller specialised on the sprint distances – the 500 m and the 1000 m – and he joined the world"s sprint skating elite in 1965. In December 1967, he equalled Yevgeny Grishin"s world record on the 500 m by skating that distance in 39.5 seconds and the next month, on 28 January 1968, he beat Grishin"s world record, to the very day five years after Grishin had set lieutenant Keller, studying dentistry at the Munich University at the time, then participated in the 1968 Winter Olympics in Grenoble.
After the 1972 speed skating season, Keller became a professional speed skater and he graduated in dentistry in 1973.
After 1974, Keller no longer participated in any international tournaments. He became a professional dentist in Munich in 1975 and only participated for a few more years in national tournaments.
World records
Over the course of his career, Keller skated 6 world records (his 500 m world record of 380 equalling the existing world record. Others would equal it too):
Source: SpeedSkatingStats.com
Personal records
To put these personal records in perspective, the last column (WR) lists the official world records on the dates that Keller skated his personal records.