The victim was killed after she came to know about their illicit relationship.

On Tuesday, the police arrested Samir Barik from Ghatakpukur in North 24 Parganas followed by the arrest of Somasree Das alias Tusi.

According to the police, Somasree and Samir first killed Srabonti, but after they found that the victim’s seven-year-old daughter Prapti had seen them committing the crime, they strangulated her also.

“Somasree and Samir were involved in an illicit relationship. Srabonti came to know about it and so she was killed,” said Superintendent of Police (Howrah), Neeraj Kumar Singh. “Srabonti had captured some photographs of the duo in a compromising position in her cellphone and started blackmailing them,” said Singh. Srabonti’s husband Partho Ghosh and Somasree’s husband Chandan Das were good friends, but the relations soured in the last few weeks.

On the day of the murder, Somasree made a call to Samir, after returning from Srabonti’s house that led the police to sense the involvement of other people in the twin murders. The police have not yet ruled out the possibility of Srabonti’s husband in the crime. On February 25, police recovered the bodies of Srabonti and Prapti from their bedroom.

“This type of the crime suggests that these were cold blooded murders and had pre-planned the killing. Both the persons were not only strangulated but they were chopped severely on their neck and throat,” Singh said.