"I think Aminul killed the two after an argument erupted with Dr Nazneen over the rape," said Moinul Haq, Assistant Commissioner (AC) of Ramna zone police.

Saiful Islam, a cousin of Dr Nazneen, filed a murder case yesterday accusing Aminul of the murder. Police then raided different areas of Aminul's home village, Akbarpur in Patnitala upazila in Naogaon yesterday, but failed to find him as of yesterday evening.

Dr Nazneen was buried in the family's graveyard in Chouddagram at Comilla. Parvin's body, meanwhile, was kept at Dhaka Medical College Hospital morgue yesterday as no one has so far claimed it.

The slaughtered bodies of Dr Nazreen Akhter, daughter of LabAid Chairman Ali Ahmed Bhuiyan, and her housemaid, Parvin, were found Monday night in Nazneen's house on the second floor of 13/1, on Central Road in Dhanmondi.

Police recovered two bloodstained vegetable cutting knives from the house, while the victim's relatives said Tk 2.5 lakh and gold ornaments were missing.

Nazneen's husband Dr Afsaruzzaman, who was in Bogra since Sunday, returned to Dhaka yesterday morning after receiving the news over phone.

According to police and Nazneen's relatives, Aminul raped Parvin when Dr Nazneen was at the house of her mother, Saleha Ahmed, on Sunday night. Parvin allegedly informed Dr Nazneen of the rape when the doctor returned home to Central Road on Monday morning. A fight then reportedly ensued between the doctor and her nephew.

"I think Aminul argued with Dr Nazneen over the matter and slaughtered the two at a point," AC Moinul told reporters.

According to police and a security guard, Aminul went out of the house with a bag at about 8:30pm, about half an hour after the murders took place.

"I heard Parvin's scream at around 8:00pm but did not care much as she used to scream at times," a guard, Moslemuddin, told The Daily Star.

"As I asked him (Aminul) where he was going, and he replied he was going to Madame's (Nazneen) brother's house," said Moslemuddin.

When Saleha later phoned her daughter at 8:30pm, no one answered, so she sent her domestic help, Manjila, to check on Dr Nazneen. But Manjila soon returned after finding the door of the doctor's apartment locked from the outside.

Some staff of LabAid later broke open the door and found Nazneen's body near the door. Parvin's body was lying on the floor of dining room.

Morgue sources said the killer stabbed Dr Nazneen in the right cheek and right wrist before slaughtering her. Parvin was stabbed in the left arm, elbow and wrist, right arm, left ear and left side of the chest.

Amirul, who passed the Dakhil examination from Mollapara Dakhil Madrasa in Naogaon, came to Dhaka a couple of months ago and was staying with Dr Nazneen.

He took Parvin six months ago to Dr Nazneen's house for domestic work.

Police, meanwhile, were quizzing guard Moslemuddin, whom they picked up in the early hours of yesterday.