Pakistani journalist Arshad Mohammed Sharif died on Sunday after the Nairobi police in Kenya fired at him at a checkpoint.

Sharif, an investigative journalist who has been critical of Pakistan military and a vocal supporter of former Prime Minister Imran Khan, had left the country two months ago after several cases, including sedition, were filed against him, reported Al Jazeera.

“I lost friend, husband and my favourite journalist today, as per police he was shot in Kenya,” Sharif’s wife Javeria Siddique said in a tweet on Monday.

In a statement on Monday, the police said they were searching for a stolen vehicle when Sharif and his brother came to a road barrier in their vehicle.

They said that it was when the journalist drove though the barrier without stopping, an official opened fire, fatally injuring Sharif.

“National Police Service regrets this unfortunate incident,” the statement said. “Concerned authorities are currently investigating the incident for appropriate action.”

The 49-year-old had fled the country in August to Dubai and then relocated to Kenya, alleging that the authorities in the South Asian country were harassing him. Sharif was booked on sedition charges after Shahbaz Gill, a close aide of Khan, had made comments deemed offensive to the military.

Following the charges, Ary News, where Sharif had worked for eight years, announced that the journalist was leaving the channel.

The Nairobi Police have said the Independent Policing Oversight Authority, which deals with complaints against the law enforcement officials, will investigate Sharif’s killing, reported the Associated Press.

“We had an incident of shooting which turned [out] to be a case of mistaken identity involving a journalist,” a senior police officer told AP. “We will release more information later.”

Meanwhile, Pakistan Prime Minister Shahbaz Sharif, President Arif Alvi and senior officials mourned the journalist’s death.

Sharif spoke with Kenyan President William Ruto and asked him to ensure a fair and transparent investigation into the journalist’s killing.

Describing the incident as “brutal murder”, Khan claimed Arshad Sharif was killed for “speaking the truth”.

“A proper judicial investigation must be instituted to examine his own statements plus evidence that other sources have,” the former prime minister tweeted. “We have descended into a state of brutality, unknown in civilised society, indulged in by the powerful against those who dare to criticise and expose wrongdoings.”

Dozens of journalists in Pakistan also staged a protests, demanding justice for Sharif.

“We don’t believe the version of the Kenyan police,” veteran journalist Hamid Mir said at a rally, adding that there were contradictions in the statements of the authorities of the African country.