The military and police have assured followers of Ibrahim Zakzaky, who heads the pro-Iranian Islamic Movement of Nigeria (IMN), that he is alive and well.
But nothing has been heard from him since he was arrested with his wife on December 13, fuelling fears about his health and the potential for a new security threat Nigeria could do without.
Human Rights Watch have claimed soldiers killed "at least 300" IMN members in the raid in the ancient city of Zaria, in the northern state of Kaduna that began the previous day.
Nigeria's military, who alleged IMN members tried to "assassinate" chief of army staff General Tukur Yusuf Buratai, dismissed the claimed death toll, calling it "unsubstantiated".
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Diplomatically, Iran is watching events closely and has voiced its concern about the situation while there were protests outside the West African country's embassy in Tehran.
Contradictory statements from Nigeria's security services on Zakzaky's whereabouts have added to the uncertainty and sparked anger among his followers.
Buratai himself said on December 17 that Zakzaky had been transferred to "the relevant authorities for prosecution", according to local media reports.
With Zakzaky reportedly shot four times and gravely injured, rumours swirled the police were buying time to allow him to recuperate, fearing a backlash if he was seen in poor health.
On December 29, federal police spokeswoman Olabisi Kolawole was quoted as telling one newspaper Zakzaky had been charged with "criminal conspiracy and inciting public disturbances".
"He has been remanded in prison custody and the case adjourned," Kolawole was quoted as telling The Punch daily.
But Kaduna prison chief Abubakar Argungu said the next day: "We only have 191 followers of the Shiite sect in our custody. But we do not have their leader, Ibrahim El-Zakzaky, with us.