HARARE, Zimbabwe (AP) — An attorney for four American volunteer health workers says Zimbabwe has dropped charges against them alleging they worked at an HIV/AIDS clinic and orphanage without proper medical licenses.

Lawyer Jonathan Samukange said the four were given their passports back and plan to fly back to the U.S. later Wednesday. He said prosecutors conceded the health workers were "doing good work" for the Allen Temple Baptist Church of Oakland, Calif. which operates the Mother of Peace Orphanage outside Harare.

Six health workers, including a New Zealand national and a Zimbabwean doctor, were arrested Sept. 10 and spent three nights in police cells.

Samukange said the four Americans, one a medical doctor, were now free to reapply to return to work in Zimbabwe.