* Head of criminal investigations seized at gunpoint
* Tests on charred body show it another person (Updates with tests on body, quote)
By Ghaith Shennib
BENGHAZI, Libya, Jan 3 (Reuters) - A police investigator was missing after being abducted in the militia-ridden Libyan city of Benghazi, police said on Thursday, but tests on a charred body showed it was not his.
The corpse charred with hydrochloric acid and found in the Buhmeida district was not that of the missing Captain Abdel-Salam al-Mahdawi, head of the city's criminal investigation unit, Prime Minister Ali Zeidan said.
"The body that was found in Benghazi was that of another man's and not Captain al-Mahdawi," Zeidan told reporters. "We wish that he is returned home safely to his family."
Al-Mahdawi was seized at gunpoint late on Wednesday night as he was poised to name suspects in the murder of a former Benghazi police chief, officials said.
"He was taken by force under the threat of weapons from a location close to the criminal investigation office," said a police official who declined to be named because he was not authorised to speak to the media.
Benghazi, cradle of the uprising that ended the rule of longtime leader Muammar Gaddafi, has been plagued by poor security and assassinations of police and military personnel by militias.
The U.S. ambassador to Libya and three other Americans were killed in an attack on the U.S. consulate in Benghazi in September.
Police and legal experts have shied away from investigating the attack because they say they have not been guaranteed protection from the groups they believe were responsible. (Additional reporting By Hadeel Al-Shalchi; Writing By Hadeel Al-Shalchi; Editing by Michael Roddy)