According to World Watch Monitor Jeff Woodke, who worked for a branch of YWAM, was abducted by unknown assailants late in the evening of Friday 14 October from the town of Abalak in northern Niger.
Woodke's condition or whereabouts are still unknown. His captors were tracked to neighbouring Mali by Nigerian authorities.
No group has publicly claimed responsibility for the kidnapping.
Jeff Woodke's current Facebook profile picture
The missionary's family has said they have been in contact with US authorities and a foreign hostage negotiator.
Although a couple of ransom demands have since been received – one asking for $10 million prisoner release - they said both demands were determined by authorities to be bogus.