Five days after the kidnapping, on January 9, the girl's body was found on a garbage heap in the city, and the autopsy revealed that she was raped before being strangled to death.
The grieving father said that police did not shoulder their responsibilities.
The girl's parents, who had been on a pilgrimage in Saudi Arabia, on Wednesday flew back and told reporters at Islamabad airport that they would not bury their daughter until her killer was arrested.
"I'm a mother and that is why I'm sitting here with my daughter", Naz was quoted as saying by The Times of India report. As many as 10 incidents took place in the first six months of 2017. Punjab CM Shahbaz Sharif has announced a financial aid of Rs 3 million to the families of those killed by firing, and said that jobs would be given to two members of each family, Dawn reported.
A police constable on Tuesday recovered Zainab's body from a trash heap.
The rape and murder case, the 12th such incident in the region, led to massive protests.
"We want the culprit to be brought in front of us".
It is pertinent to mention here that 11 minor girls were kidnapped and then murdered in Kasur during the last one year; however, police didn't arrest a single culprit.
An autopsy has confirmed that Zainab was strangled and sodomized and suggests she was raped, the medical officer who carried out the examination, Dr Quratulain Atique, told CNN.
Zainab went missing on January 4 in Kasur, Punjab.
Pakistan cricketers Mohammad Hafeez and Mohammad Amir also tweeted condolences to Zainab's parents.
Following the violence and increasing global attention in the case, the hashtag #JusticeForZainab began trending worldwide, and famous Pakistani figures including Nobel Peace Prize victor Malala Yousafzai and members of the national cricket team joined a chorus of disgust at the crime. Pakistan needs to reevaluate how it deals with such crimes, especially those against children.
"If there is any humanity, they should take action immediately."
Punjab Chief Minister Shehbaz Sharif visited the victim's family Thursday morning assuring them the culprits will be caught and punished, local media reported.
The Punjab government has offered a reward of 10m rupees (£66,460) for information leading to the killer's capture, as well as compensation for the protesters killed on Wednesday.