(CNN) A suspect is in custody and an investigation is underway after a US diplomat was found dead Friday in Madagascar, the US State Department said.

The unnamed diplomat was found at home in Antananarivo, Madagascar.

"Our deepest sympathies go out to the family and to the US Embassy Antananarivo community," State Department spokesperson Heather Nauert said in a statement.

US investigators are working with Malagasy authorities to investigate the death, the statement said.