The Brazilian woman charged with poisoning three of her relatives with an arsenic-laced Christmas cake has been found dead in her prison cell — a day after her husband asked for a divorce.

Deise Moura dos Anjos, 42, has been locked up in pre-trial detention on murder charges since January after prosecutors accused her of killing three relatives — and attempting to kill three more — with a tainted cake she served them on Christmas Eve.

She was discovered in her cell in the southern Brazilian city of Guaíba, in the state of Rio Grande do Sul, CNN Brasil reported.

“Immediately, the staff provided first aid” and called for help, but she could not be saved, police said of the suspected suicide.

Dos Anjos’ husband, Diego, had asked for a divorce the day before her death, according to the outlet.

Tatiana Denize Silva dos Anjos, 43, Maida Berenice Flores da Silva, 58, and Neuza Denize Silva dos Anjos, 65, each died after eating Bolo de Natal — a Brazilian Christmas cake — during a holiday celebration in Torres in southern Brazil.

The family members remarked that the cake had a “bad taste” just minutes before they each started vomiting and feeling ill.

The other family members, including a 10-year-old boy, were hospitalized.

Investigators found copious amounts of arsenic in the victims’ blood — with up to 350 times the amount necessary to kill a person found in one of them. 

The dessert had been baked with flour contaminated with deadly levels of the poison, officials said.

Authorities were also investigating if she may have killed her father-in-law, who died in September, after authorities exhumed his body and found high levels of the poison.

Moura dos Anjos maintained her innocence, but local police chief Cléber dos Santos Lima said last month he was “certain that she researched, bought (…) and used the poison to kill her victims,” according to the BBC.

Police determined she had bought arsenic on four separate occasions.