Police yesterday arrested Shajahan Miah, the apartment's security guard who was on duty during the hours of the incident. His name was mentioned in the case as an aide of the murderers.

Nawshin's father Sultan Faruk, an accountant of Bangladesh Rifles (BDR), filed the case with Ramna Police Station against his brother-in-law Zahidul Haque Rintu.

In the first information report (FIR), Sultan said Rintu is a criminal and earlier on different occasions directly and over phone threatened to kill him and his family members including Nawshin as they asked him to leave their house.

Sultan said Rintu alone or with the help of others has killed his daughter. The complainant mentioned the name of the security guard as Rintu's associate.

"We arrested the guard of the house but he has not yet given any significant information," said AKM Daulat Akbar, officer-in-charge of Ramna Police Station.

Sultan is posted in Sylhet and his family has been residing in the flat since September 2005.

Investigators yesterday questioned the family of building owner Hashem Patwari and a few tenants of the apartment.

The Rapid Action Battalion (Rab) and different intelligence agencies visited the house to investigate the incident.

The autopsy of Nawshin's body was performed yesterday. Morgue sources, however, refused to make any comment if it was a case of murder or suicide. Samples were taken for viscera test.

The body of Nawshin was taken to their village home at Mathbaria in Pirojpur for burial yesterday morning.

Nawshin's friends and their guardians visited the flat yesterday and demanded immediate arrest of the murderer and exemplary punishment to him.

They said Nawshin's parents had a dream that their daughter will be a doctor someday. To pursue the dream, they always took care so that Nawshin could have a good command on subjects like biology. They were hurt when Nawshin took biology as an optional subject at the time of admission in Viqarunnisa Noon School and College.

Nawshin was not much talkative but would always wear a smile, said her friends.

Nawshin got scholarship both in classes V and VIII and used to spend most of a day's time studying at different coaching centres.