Georgy Gongadze, chief editor of the independent Ukrainska Pravda web magazine, disappeared in central Kiev while on the way home from work on September 16.
Police investigators discovered a partially buried skull in the Traschanksy forest north of Kiev Tuesday, not far from a shallow grave where three headless corpses were found earlier this month.
Ukrainska Pravda editor Alena Pritula last week identified one of the bodies as Gongadze´s by recognising a good luck charm, bracelet, and necklace on the corpse.
Ukrainian officials said final identification of the decomposing remains was impossible without DNA testing, but based on initial examinations expressed doubt that the skull in particular would turn out to be Gongadze´s.
"We have reason to believe that the head belonged to a woman," Ukrainian Prosecutor General Myhailo Potebenko told reporters.
The high-profile Gongadze case has battered the already low reputation of Ukrainian law enforcers. Ukrainian President Leonid Kuchma has appointed a special commission to oversee the investigation, and is receiving daily reports on its progress.
After two months of intense police investigation into Gongadze´s disappearance, a farmer and his son made the first apparent big break in the case by accidentally discovering the corpses while out picking mushrooms.
A rural coroner compounded police embarrassment by issuing a certificate for Gongadze´s death to an investigating journalist, rather than waiting for family members to identify the corpse.
When Gongadze´s wife and the Kiev press corps arrived at the Traschansky morgue later that day to check, they learned unidentified officials had relocated the remains to an undisclosed location.
Potabenko confirmed his detectives had taken custody of the headless corpse, but declined to say where it was being examined, who was examining it, or when findings might be released to the public.
"At this point we can not provide answers to those questions," he said.
Ukrainian lawmakers, charging the police investigation was incompetent, on Monday called for an examination of the corpse by foreign forensics experts.
Ukrainska Pravda is one of Ukraine´s few independent news sources. Gongadze´s disappearance was linked to articles exposing corruption and manipulation of the judicial system by high Ukrainian officials, or Gongadze´s personal debts, prosecutors have said.
Journalists in the former Soviet republic are frequent targets for threats and even beatings, but media contract killings are not common.
(la/dpa)