Leah's family is still in mourning while other parents celebrate the return of their children.
110 schoolgirls had been kidnapped by the terrorists on February 19, 2018, during an attack on their school but 104 were released on Wednesday to wild jubilation in Dapchi.
One of the schoolgirls, Khadija Grema, told Channels Television on Wednesday that five of her schoolmates died of heart attack and stress as a result of the long trip while the terrorists have held on to 15-year-old Leah for religious reasons.
"There's one of the girls that wasn't freed because she is a Christian, she was held back," Khadija said.
According to a report by Channels, Leah's mother, Rebecca Sharibu, was in a deep state of mourning on Wednesday while other parents celebrated the return of their children.
Her sister was also reported to have fainted and might even have slipped into a coma after hearing the news that her sister was not among those that were released.
Leah's father, Nathan Sharibu, was the first to speak about the issue on Wednesday when he disclosed during an interview that his daughter was not released by the terrorist group because she refused to renounce her Christian faith like they demanded.
He said he discovered this after speaking to some of the released girls on the phone and that he's proud of his daughter's decision.
He said, "Right now, I'm not in Dapchi. I'm in my duty post. I called the parents who are in Dapchi. I was informed that my daughter was not released. All of them have been released but they said some were dead there, but my daughter is alive.
"They said she was a Christian that's why they could not release her. They said she cannot be released until she becomes a Muslim. And my daughter said she would never be a Muslim.
"I spoke with about five to six of them whose daughters have been released. They are presently with their daughters in Dapchi. They were dropped by the Boko Haram people in Dapchi town this morning.
"I am happy because my daughter did not denounce her faith. They refused to release her because she refused to convert to Islam."
The Federal Government has categorically denied reports that it paid a ransom to Boko Haram to secure the release of the girls.
Minister of Information and Culture, Lai Mohammed, said the "unconditional" release of the girls was as a result of back-channel efforts achieved through "the help of some friends of the country".
After the 104 schoolgirls, alongside two other released hostages, were documented and profiled in Dapchi on Wednesday, they were transported to Borno State capital, Maiduguri, for onward movement to Abuja.
At the 105 Air Force Composite Command, Maiduguri yesterday, the Theatre Commander, Operation Lafiya Dole, Major General Rogers Nicholas, presented the released girls to a delegation of the Federal Government.
The delegation was led by Lai Mohammed, and included Minister of Interior, Abdulrahman Dambazau and Minister of State for Foreign Affairs, Khadija Bukar-Abba.
The released girls, alongside their parents and some aid workers, boarded a Nigerian Air Force aircraft to Abuja late on Wednesday.
Boko Haram militants invaded Government Girls Science and Technical Secondary School in Dapchi, Bursari local government area of Yobe on Monday, February 19, 2018, and abducted 110 schoolgirls.
According to accounts by residents, the terrorists invaded the town around 7 pm in over 18 gun trucks mounted with high caliber weapons.
The abduction was a repeat of another Boko Haram attack that happened when militants invaded Government Girls Secondary School in Chibok and kidnapped 276 female students in April 2014.
After several escapes and releases, 112 of the girls remain in captivity of the deadly terrorist group.