The Committee to Protect Journalists today called on Pakistani authorities to investigate and promptly bring to justice the killers of journalist Sohail Khan. Khan, a reporter for the Urdu daily K2 Times, was shot dead while driving in Haripur, Khyber Pakhtunkhwa province, yesterday, according to multiple newsreports.

News reports said that Khan received threats shortly after writing a story about the arrest of an alleged drug dealer named Musarrat Iqbal. Khan had filed an application at the district police office requesting protection on the day that he was killed, Iqbal Khattak, director of the media watchdog organization Freedom Network, told CPJ.

“We condemn the killing of Sohail Khan in Pakistan, and urge authorities to carry out a thorough and transparent investigation and bring all those involved in the killing to justice,” said CPJ Asia Program Coordinator Steven Butler in Islamabad. “Pakistani authorities must send a clear signal that they are committed to stamping out the culture of impunity that continues to thrive in the country.”

In a report today, The Associated Press cited a Haripur police official as saying that Khan was killed because of his reporting. The official said police were searching for Ali Sher and Himayun Iqbal, the sons of the jailed drug dealer. The sons are suspected of ambushing Khan’s car and killing him, the police official said.

The Freedom Network tweeted a photo of the Urdu-language first information report filed on Khan’s killing. Khattak told CPJ that two people listed in the report are Iqbal’s sons.

When CPJ called the district police office in Haripur for comment, the person who answered said he didn’t know about the case and that no one else was available.

Last year, K2’s Haripur bureau chief Bakhsheesh Elahi was shot dead. Police have not made any arrests in that case and CPJ is still investigating to determine if journalism was the motive. At least 33 journalists have been murdered in retaliation for their work in Pakistan since 1992, according to CPJ research. In a special report released last month, CPJ found that while fatal violence against the press has declined in recent years, journalists’ fear and self-censorship have increased.