A packed Nigerian court heard testimony on Monday that a 14-year-old girl admitted to killing her 35-year-old husband with rat poison, and signed a police confession with a thumbprint because she cannot write.

Wasila Tasi’u, from a poor and deeply conservative Muslim family, has been charged with murdering her husband Umar Sani days after their marriage in northern Kano state.

Because she did not understand English, homicide investigator Abdullahi Adamu translated her statement from the Hausa language dominant in the region and gave her the document to sign.

Wasila Tasiu: 14 year old girl charged with murder

She could not write her name, so “she had to use a thumbprint,” he told the court during his testimony on the last day of the prosecution’s case.

The state’s lawyers, who are seeking the death penalty, also called to the stand Tasi’u’s “co-wife”, a term referring to the woman — identified as Ramatu — whom the deceased farmer had married previously in a region where polygamy is widespread.

Ramatu said she got along well with Tasi’u and that the two had prepared the food together on April 5, the day Sani died.

She testified that because it was Tasi’u’s turn to share a bed with Sani, Tasi’u was also entitled to serve him his meal.

“After putting the food in the dish I didn’t see anybody put anything in it,” Ramatu said.

She told the court she saw her husband sometime later being helped back to the house by a neighbour, unable to walk and foaming at the mouth.

As she spoke the court was overflowing, with people peering in through the open windows and a crowd so large it spilled out of the gallery door.

The case has sparked outrage among human rights activists who say Nigeria should be treating Tasi’u as a victim, noting the possibility that she was raped by the man she married.

But others in the region, including relatives of the defendant and the deceased, have rejected the notion that Tasi’u was forced into marriage.

They have said that 14 is a common age to marry in the deeply impoverished region and that Tasi’u chose Sani from among many suitors.

A motion by defence lawyers to have the case moved to juvenile court was rejected, despite claims by human rights lawyers that she is too young to stand trial for murder in a high court.

Further complicating the case is the role of sharia (Islamic law) in northern Nigeria, which allows children to marry according to some interpretations.

While sharia is technically in force in Kano, law enforcement officials have no guidelines concerning how it should be balanced with the secular criminal codes, creating a complex legal hybrid system.

According to Human Rights Watch, Nigeria is not known to have executed a juvenile offender since 1997, when the country was ruled by military dictator Sani Abacha.

The trial has been adjourned until February 16.