A policeman was arrested on Wednesday on suspicions that he facilitated the murder of a school principal in Karachi's Parsi Colony earlier this month.

The victim, Ambreen Fatima, had allegedly been shot dead by her husband, Aliul Hasan, on December 10. The murder had initially been framed as a case of a mugging gone awry.

Police had previously arrested Hasan, his second wife Sahar Shams and his brother-in-law, Balaach. All three had been remanded to police custody for interrogation till December 28.

Police have now added policeman Bilal, who is Sahar Shams' brother, to the list of people arrested in connection with the murder.

The Station House Officer of Karachi's Soldier Bazaar area, where the murder took place, told Dawn that police had also recovered the weapon believed to have been used in the crime from Bilal.

A raid was also conducted to nab yet another police officer, Danish, and his father, Gul Nawaz, but the duo have absconded, the police official said.

The pistol recovered, police say, originally belonged to Nawaz, whose son lent it to fellow cop Bilal, who in turn forwarded it to Sahar, who then gave it to her husband.

The police believe Ambreen's murder was an outcome of her husband’s secret marriage to Sahar. Sahar wanted to make the marriage public, prompting the main accused to kill his first wife.