Since sacking Ranil Wickremesinghe, Maithripala Sirisena has taken the police under his direct control.
Sri Lanka's president ordered the removal of a police chief investigating alleged crimes by the family and associates of his preferred candidate for prime minister Mahinda Rajapakse, officials said Monday.
The island nation has been paralysed since October 26 when President Maithripala Sirisena controversially sacked prime minister Ranil Wickremesinghe and replaced him with former rival Rajapakse.
Wickremesinghe insists he is still prime minister, leading to a constitutional deadlock in Sri Lanka.
In the latest twist in the ongoing crisis, Chief Inspector Nishantha Silva was transferred from the Criminal Investigation Department on Sunday as he pursued inquiries into the close family and allies of Rajapakse, an official told AFP.
Since sacking Wickremesinghe, Sirisena has taken the police under his direct control.
Silva investigated the killing of 11 children between 2008-2009 and had secured an arrest order last week against the country's top military official when he was shifted on Sunday, an official said.
"He was about to arrest Admiral Ravindra Wijegunaratne when his marching orders came," a senior police official told AFP.
"This is a serious blow to half a dozen high profile investigations."
Wijegunaratne has remained the chief of defence staff.
Silva was also pursuing the killers of editor Lasantha Wickrematunga and investigating Rajapakse's former defence secretary brother Gotabhaya, who is accused of defrauding the state.
Gotabhaya Rajapakse was indicted in September on charges of siphoning off over $250,000 in state funds to build a memorial for his parents.
Silva was also investigating an alleged corrupt aircraft purchase from Ukraine when Gotabhaya Rajapakse was in power between 2005 and 2015.
Sacked PM Wickremesinghe has accused Rajapakse of seeking to grab power again in order to sabotage the court cases against his family and associates.
In August, a special court charged Rajapakse's chief of staff with embezzling millions of dollars from a state insurance firm.
Rajapakse's top civil servant, Lalith Weeratunga, was convicted of misappropriating $4 million and sentenced to three years in prison.
Two of the former president's three sons have also been charged with money-laundering and other relatives face corruption allegations.
The former president was questioned in August over the 2008 abduction and torture of a journalist. He denies any wrongdoing and has accused the government of a witch-hunt.