The lifeless body of Stephen Ajah was found on the Ozalla-Agbani Road in the early hours of Monday.
Reports said a military helicopter had allegedly shot at civilians who were ferrying foodstuffs and household items.
On June 24, Chidinma Ojukwi told reporters that he stabbed the deceased to death after he attempted to have sex with her. She now denies that account in a latest interview.
The war crimes tribunal is also seeking to bring Boko Haram elements to justice for crimes against humanity.
The anti-graft office said its detectives are investigating a corruption case involving a staff member of the newspaper.
The magistrate gives the police two weeks to submit their report into the criminal complaint against the activists.