The state Police Public Relations Officer, Mr Chidi Nwabuzor, confirmed the arrest on Wednesday.
It was gathered that deceased, Helen Adodo, died after her head was smashed with a stone at her residence on Guobadia Street, Benin.
It was learnt that Amos had been living with the septuagenarian, who was down with a stroke, since March 2018.
Unidentified persons had reportedly sneaked into the residence of the late Adodo at about 7am on Tuesday.
They were said to have blindfolded Amos before killing the septuagenarian.
The incident attracted residents and sympathisers, some of whom wailed as they saw the lifeless body of the victim.
A man, suspected to be the son of the deceased, expressed shock over his late mother’s death, adding that she did not have a disagreement with anyone in the neighbourhood.
A clip obtained by Punch on Wednesday showed the teenager confessing to the crime in the presence of some residents in the area.
In the clip, Amos alleged that she was possessed by a “spirit,” adding that she did not know the number of times the deceased was hit with the stone as she did not know what came over her.
The teenager, however, noted that the deceased did not offend her.
She said, “When I took some plates outside, I took a broom and swept the ground. I stood on the stone and looked up and down.
After I did that, something entered my body. I stood on a stone again and looked up and down.
“I took the stone to the veranda and sat on it. Later, I entered the room and did not know when I hit her head with the stone. I did not know what came over me. It was a spirit. It told me to kill her. She did not offend me.”
The Police Public Relations Officer, Mr. Chidi Nwabuzor, stated that the command received a distress call over the matter around 8.30am.
Nwabuzor also disclosed that the case had been transferred to the State Criminal Investigation and Intelligence Department.
He said, “The (distress) caller said that two men came into the residence, murdered the woman and went away.
“However, it was revealed today (Wednesday) that a girl who was staying with her, Anna Amos, was the one that killed the woman. The Anna Amos has confessed that she killed the woman.
“Anna Amos is 14 years old and by law, she is still a minor. But we will do all we can to get to the root of this matter. We will not rely on the confession of that girl because it may not be the girl that is responsible for the killing of that woman.
“Perhaps somebody else did (killed her) and asked this little girl to own up as the culprit. Investigation is ongoing.”