It wasn't the Napa syrup that killed the two children at Durgapur village, after all. It was their mother who had poisoned them so that she could marry her boyfriend.

"After a thorough investigation, we have found evidence that the mother in association with her boyfriend committed the killings," said Mohammad Anisur Rahman, superintendent of police (SP) of Brahmanbaria, at a press conference yesterday.

Their mother, Rima Begum, was having an extramarital affair with one Shafiullah, who she met while working at a rice mill in Bagoir area in Ashuganj upazila.

Shafiullah agreed to marry her on the condition that she leaves behind her children Yasin Khan, 7, and Morsalin Khan, 5.

They hatched the plan to kill the two boys. On the evening of March 10, Rima fed her two sons poisoned sweets provided by Shafiullah.

The boys fell sick and were initially taken to Ashuganj Upazila Health Complex. They were sent to the Brahmanbaria General Hospital. Curiously, the boys were not admitted to the hospital.

Yasin died on the way home from the hospital, while Mursalin breathed his last upon reaching home, Rahman said at the press conference.

Rima claimed to local journalists that her sons fell ill after consuming Napa syrup bought from a local pharmacy and started to vomit. Later, they died.

The children's death drew the attention of all concerned across the country.

The Directorate General of Health Services, the Directorate General of Drug Administration and Brahmanbaria General Hospital authorities formed three investigation committees to probe the deaths.

The drug administration authorities collected samples of Napa syrup of particular batches, including the one in question, and tested them in labs. But the authorities found no harmful ingredients.

Meanwhile, on Wednesday, the children's father Ismail Hossain Khan, who is visually impaired, filed a case against Rima and her 'boyfriend' Shafiullah.

The police investigated the thread further and found that Rima had called Shafiullah 15 times on the day the children died.

During the investigation, police found that the family took the boys to the Brahmanbaria General Hospital and bought a ticket for taking treatment in the emergency department. But they fled from the hospital without receiving treatment.

In the early hours of yesterday, police arrested Rima, who admitted to her crime in primary interrogation, Rahman said.

Yesterday, Rima was produced before the Chief Judicial Magistrate's Court of Brahmanbaria, where she also gave a confessional statement, said Kazi Dider Ul Alam, inspector of Brahmanbaria Court Police. Later, the court sent her to jail, he said.