Congo's prosecutor general says an American who was a security guard for a top opposition leader and was arrested in April has been released.

Victor Mumba Mukoko said Wednesday that Darryl Lewis will return to the United States, though the case is not closed.

Congo authorities arrested Lewis during an opposition demonstration in Lubumbashi. A Congo court has accused opposition leader Moise Katumbi of hiring mercenaries as security guards. The charges were announced the same day Katumbi said he would run for the November presidential election.

Katumbi's hearing began last month but was postponed after police fired tear gas outside the hearing. He fell ill and was medically evacuated from Congo.

Tensions surround the elections, which the opposition fears will be postponed to keep President Joseph Kabila in power longer.