Amna with the help of her husband Arshad and son Adil severely tortured her 22-year-old pregnant daughter Muqadas before she slit open her throat with a knife.
"We tracked down the prime suspects - Amna and Adil through mobile data and arrested them from a hideout in Gujranwala," Superintendent of Police Nadeem khokhar said, adding that raids are underway to arrest other suspects.
Muqadas, a resident of Butranwali, Gujranwala, some 80 kms from Lahore, contracted love marriage with Taufeeq of her locality against the will of her family some three years ago.
According to police, Amna recently contacted Muqadas and told her that the family had pardoned her. On Thursday, when the eight-month pregnant Muqadas was present at a clinic in her locality for a check-up, Amna reached there and took her to her house where she was murdered.
More From This Section
Shafique, brother-in-law of Muqadas, told police her parents pledged to kill her for earning bad name for the family.
Last week Zeenat, 18, was burnt alive by her mother in Lahore for marrying a man of her own choice.
At least 1,100 women were killed in the name of honour in Pakistan last year by their relatives on the pretext of defending what is seen as family honour.