A Boko Haram splinter group loyal to the Islamic State has killed one of the health workers kidnapped from Kala-Balge, Borno State, Saifura Khorsa, a midwife with the International Committee of Red Cross.
The International Committee of the Red Cross condemned the "tragic killing" of Khorsa in a statement released on Monday.
"We are devastated by the murder of our colleague Saifura," said Eloi Fillion, the head of the ICRC delegation in Abuja.
The terrorist group also threatened to kill Hauwa Liman and Alice Ngaddah who were abducted alongside Khorsa in March 2018, as well as Leah Sharibu, the remaining Dapchi schoolgirl in Boko Haram captivity.
Leah, who has been in captivity for over 200 days, is one of the 100 schoolgirls kidnapped in Dapchi, Yobe State, by Boko Haram. But she was held back when others were released because she refused to renounce her Christian faith.
"The girls that returned said Leah said she will not deny Christ or turn to be a Muslim," Leah's father, Nathan said in an Interview.
The insurgents, however, claimed that they had contacted the government over the captives but did not get any response.
"We contacted the government through writing and also sent audio messages but the government has ignored us. So, here is a message of blood," said a spokesman of the group who did not give his name.
This may be connected to as the sect late August released a 35-second online audio of Sharibu pleading for an urgent intervention by President Muhammadu Buhari to facilitate her rescue.
"I am Leah Sharibu... I am calling on the government and people of goodwill to intervene to get me out of my current situation".
The recorded audio came months after the Nigerian government said negotiations for the rescue of the lone Christian girl were still ongoing.
The government admitted, however, that efforts to secure her release by the insurgents had been tortuous and complicated.
"The other nurse and midwife will be executed in a similar manner in one month, including Leah Sharibu," the sect threatened.
This latest threat may be part of the indications, as predicted by Ahmad Salkida, a journalist with the knowledge of Boko Haram insurgency and Lake Chad crisis, that the sect may be on the verge of launching a large-scale attack in northeast Nigeria.
"The insurgents are busy piling up arms by overrunning one military base, after another, for something "big" and what could that be," he tweeted on Saturday.
The rising regularity of Boko Haram attacks suggests that Salkida's warning should be taken seriously.
"When attention was on #ISWAP attack on Guzamala yesterday, the group staged another daring attack on a military facility in Baga, Kukawa, on the shores of the #LakeChad," Salkida said in another tweet on Sunday.
This warning is coming after Buhari in May said they have been "degraded" instead of "defeated" in what seemed to be a tacit acknowledgement of the difficulty of the task of curtailing the growth of the insurgents.
"The capacity of the insurgents has been degraded, leading to the re-establishment of the authority of government and the release of captives including, happily, 106 Chibok and 104 Dapchi girls, and over 16,000 other persons held by the Boko Haram," Buhari said in a Democracy Day speech on May 29, 2018.
Recent attacks carried out by the two factions of Boko Haram indicate that the claim of them being defeated or degraded may have come too soon.
However, while reacting to the murder and the threats the Nigerian Government pledged its commitment to rescuing all captives.
"The government of Nigeria strongly condemns this reprehensible and inhuman act. No religion permits the killing of the innocent," Garba Shehu, his senior special assistant on media and publicity said on Monday.
The president, therefore, appealed to Nigeria's international partners and everyone with an influence on the sect to prevail on it "to stop these acts of extreme barbarism."