The delayed action on the assassination bid comes after Pakistan’s Supreme Court gave a 24-hour deadline to open a criminal investigation as Mr Khan raised questions over the delay in filing the complaint.
Punjab police opened a criminal investigation late on Monday night against assailant Naveed Mohammad Basheer, the prime accused in the case who was arrested from the rally where Mr Khan was shot in the leg.
The complaint did not name any of the three people — current prime minister Shehbaz Sharif, interim minister Rana Sanaullah, and a senior Pakistan army major-general Faisal Naseer — accused by Mr Khan and his party of hatching a plot to assassinate him.
Last week, Mr Khan survived the assassination attempt during his anti-government protest rally in the eastern Pakistan town of Wazirabad as he waved to supporters from the roof of a container truck.
He was leading a convoy six days into a march to Islamabad demanding early elections. The attack killed one and wounded at least 10.
There was a deadlock on the registration of the complaint (commonly known as FIR or First Information Report in South Asia) after Mr Khan named a senior army official as one of the people behind orchestrating the attack on him.
“I wonder if I, being the former prime minister of Pakistan, can’t get an FIR registered regarding an attack on me, what will happen to the common man,” Mr Khan had said, raising the issue of delay in filing the complaint.
The accused, who has confessed to shooting Mr Khan at the rally in a video statement, has been charged under the country’s Anti-Terrorism Act among other charges.
Mr Khan called it a “farcical FIR” and his party members said they are going to challenge it in the apex court.
The country’s Supreme Court on 7 November directed the Punjab police chief to file a complaint into the attack on Mr Khan and other members of his party.
Pakistan’s chief justice Umar Ata Bandial warned of suo moto action if the FIR was not registered within 24 hours.
“Tell us when the FIR will be registered,” he said, adding that there should be a concrete reason for not registering it.
“How will an investigation be initiated without it? And without an FIR, even evidence can be altered,” he added.
Mr Sanaullah, who has denied Mr Khan’s allegation of hatching the assassination attack, said on Tuesday the suspect was self-motivated.
“The things we got from his cell phone showed that he was fully motivated, fully committed,” he told a news conference.
Mr Khan on Wednesday said that he will receive the forensic report of the attack on him and it will prove that “there was more than one shooter”.
In an interview with TRT, Mr Khan claimed that the person who has been arrested was not a religious fanatic, “but he was a trained shooter”.
“There was this guy who fired the first volley … then there was another volley [that] came in over our heads because we were falling,” he said.