An unidentified person paid a ransom that freed three missionaries kidnapped by a gang in Haiti under an agreement that was supposed to have led to the release of all 15 remaining captives early last month, workers for their Ohio-based organization have confirmed.

The person who made the payment was not affiliated with Ohio-based Christian Aid Ministries, and the workers say they don't know who the individual is or how much was paid to the gang, which initially demanded $1 million per person. Internal conflicts in the gang, they say, led it to renege on a pledge to release all the hostages, fr...