BEIRUT (AP) — A prominent Lebanese publisher and strong critic of the Shiite militant Hezbollah group was found dead in his car Thursday morning, shot in the head with two bullets, a security official said.

Lokman Slim, a longtime Shiite political activist and researcher, was found in Addoussieh village in the southern province of Nabatiyeh, after he had gone missing for several hours, the official said.

His wife, Monika Borgmann, and his sister had posted on social media earlier that Lokman was not answering his phone for hours and he had not been seen since Wednesday evening.

The circumstances of Slim’s death were not clear and there were no immediate details.

The security official, who spoke to The Associated Press on condition of anonymity in line with regulations, said an investigation is underway to determine what happened.

Slim and his wife lived in the southern suburbs of Beirut where they ran Umam Productions, a film production house. His family owns a publishing house and Slim often hosted public debates and political forums.