Farzana Parveen was killed on Tuesday outside the High Court in the eastern city of Lahore by more than two dozen attackers armed with bricks, including numerous relatives, for marrying against her family’s wishes.
The brazen, brutal nature of the killing, in broad daylight in the centre of Pakistan’s second largest city, has triggered outrage around the world.
Police were apparently at the scene, but did not intervene.
Prime Minister Nawaz Sharif on Thursday told Punjab Chief Minister Shahbaz Sharif, who is his brother, to take immediate action on the case.
“Special investigation teams set up by police on the directive of the chief minister arrested four more people including an uncle and two cousins of the slain woman and a driver on Thursday night,” senior police official Zulfiqar Hameed told AFP on Friday.
The new arrests bring the number held over the killing to five, after Parveen’s father was detained at the scene of the attack.
Shahbaz Sharif has ordered police to round up all those involved within 24 hours.
He has also directed that the case should be heard in an anti-terrorism court. This should mean it moves more quickly than in a regular court.