The man, a German resident of the Spanish island of Tenerife, was wanted as a suspect in the murder of a 38-year-old woman, also German, who was found dead in the river Rhine near a popular swimming spot in the Swiss commune of Tägerwilen on May 15th.
According to a statement by Thurgau cantonal police, an autopsy revealed that the victim died as a result of massive head injuries.
Police investigations revealed that the 59-year-old had met with the victim prior to her death.
A witness saw the two together near the place where the woman's body was later discovered.
Stefan Haffter, spokesman for the Thurgau public prosecutor, told newspaper Blick that the suspect and the victim were “intimate acquaintances” but did not elaborate further.
The suspect arrived in a car with Spanish licence plates, the witness told police.
The Swiss prosecutor has requested the man's extradition from Spain to Switzerland.