The Islamabad police have so far arrested six suspects in the case of the rape and murder of a 10-year-old in Chak Shahzad.
The police said that 793,000 calls have been scrutinized and while 1,587 phone numbers found suspicious. It has interrogated 50 people, both men and women.
Experts from the Punjab Forensic Agency have also been requested to help with the DNA reports.
Farishta went missing on May 15 at 5:30pm from her house in Chak Shahzad. Her body was found in a nearby forest on May 20. One of the issues raised during the investigation was that the SHO of the Shahzad Town police station initially refused to register a case of her disappearance. He told the family that it seemed as if the girl had run off herself.
He has since been suspended.
Prime Minister Imran Khan has also taken notice of the case. A judicial inquiry is also under way.