Forensic experts have confirmed that a banned rat poison was used to lace an Easter egg that killed two children in Brazil, in a case that has shocked the nation.

The revelation comes after a teenage girl became the second victim of the Easter egg killer accused of sending poisoned chocolates to her ex's new love.

Evelyn Fernanda Rocha Silva, 13, died of multiple organ failure on 22nd April after a five-day fight for life in a hospital intensive care unit in Imperatriz, a city in the state of Maranhao, Brazil.

Picture shows Luis Fernando Rocha Silva, 7, his mother, Mirian Lira, 32, and his sister, Evelyn Fernanda, 13. Luis Fernando died after eating a poisoned Easter egg and his mother and sister are in critical condition in Imperatriz, Brazil. Note: Private photo taken from local media. (Newsflash/NX)

She and her seven-year-old brother Luis Fernando fell ill almost instantly after eating the chocolate mini eggs delivered to their mum, 32-year-old Mirian Lira Silva.

Luis died just hours later on 16th April and the siblings' seriously ill mother is still in hospital.

Police believe the killer chocs were sent by Jordelia Pereira Barbosa, 36, the ex-wife of Mirian's new boyfriend.

Picture shows Luis Fernando Rocha Silva, undated. He died after eating a poisoned Easter egg and his mother and sister are in critical condition in Imperatriz, Brazil. Note: Private photo taken from local media. (Newsflash/NX)

Accused Barbosa was seen in CCTV footage buying the box of luxury mini Easter eggs disguised with sunglasses and a black wig hiding her dyed blonde hair.

Investigators say Barbosa then poisoned the chocolates and sent them by courier to Mirian who unsuspectingly shared them with her children on 16th April.

Horrifyingly she sent a note with them saying: "With Love To Mirian Lira - Happy Easter".

After the delivery Mirian received an anonymous call asking if she had received the package.

Picture shows Jordelia Pereira Barbosa, 35, undated. She was arrested for poisoning an Easter egg and sending the chocolate to a family in Imperatriz, Brazil. Note: Private photo taken from local media. (Newsflash/NX)

The Maranhao Civil Police say Barbosa was arrested the next day on a long distance coach heading for Santa Ines, a city nearly 200 miles (320 kilometres) away.

Officers also seized two wigs, receipts, cards, scissors, a saw knife and what appeared to be drugs, say Imperatriz murder squad police.

Barbosa has confessed to sending the chocolate eggs but denied adding the poison.

Forensic testing, however, has now confirmed that the chocolates were laced with 'chumbinho', a banned rodenticide often used illegally in Brazil.

Picture shows the poisoned egg and the note, undated. Jordelia Pereira Barbosa, 35, was arrested for poisoning an Easter egg and sending the chocolate to a family in Imperatriz, Brazil. Note: Police photo taken from local media. (Newsflash/NX)

Maranhao Secretary of Public Security Mauricio Martins explained: "The evidence suggests that the crime was motivated by revenge, by jealousy, considering that the perpetrator’s ex-husband is currently the partner or boyfriend of the victim, who was poisoned along with her two children."

Barbosa remains in custody at the Sao Luis Women's Rehabilitation Prison Unit (UPFEM).

(MJ Leidig/newsX)