The Chinese embassy in the Central African Republic had a stark warning for its compatriots in the landlocked nation: Do not leave the capital city of Bangui. Kidnappings of foreigners were on the rise, and any Chinese person outside Bangui was to leave those areas immediately.

Less than a week later, on March 19, a group of gunmen stormed a remote gold mine far away from Bangui and killed nine Chinese workers.

The Central African government has said that it investigated the massacre and concluded that a leading rebel group had orchestrated it. The rebels have denied the allegation and blamed a third party that operates in the country — Russia’s Wagner mercenary group, which has, in turn, accused the rebels. None of the sides has presented evidence for its claims.

The investigation has left a trail of unanswered questions about the motives and methods of the attackers. More than a dozen Central African soldiers were supposed to be protecting the site, according to a diplomat briefed on the investigation, but on the day of the attack, only four of them were there and all survived.

The victims have not been identified, and their bodies were cremated shortly after the attack. One local mayor said the workers were shot at close range.

The murkiness around the killings underscored the growing security challenge facing the Chinese government as Chinese companies have rapidly expanded their activities around the world, often stepping into the middle of conflict zones.

New York Times News Service