Govind Pansare was shot at on February 16, 2015 in Kolhapur and died of his injuries a few days later.
The Bombay High Court on Monday said it was "unhappy" with the probe report submitted by the Special Investigation Team (SIT) of Maharashtra CID on the killing of CPI leader Govind Pansare.
A bench of justices SC Dharmadhikari and GS Patel noted that the SIT report did not contain any "independent steps" it had taken during the course of its probe and said "things are not moving".
It was hearing petitions filed by the family of Govind Pansare and rationalist Narendra Dabholkar seeking a court-monitored probe in their killings.
The court said the only reason it was refraining from passing a more critical order was that it realised the officer concerned had failed to make any significant progress in the past few weeks due to floods in Kolhapur.
"The investigating officer has failed to list any independent steps in this report. Whatever you (SIT) have stated here is all resting on the probe in other cases (the probe into killings of rationalist Narendra Dabholkar and journalist Gauri Lankesh)," the bench said.
"We must convey our unhappiness. Things are not moving. We are refraining from passing critical order against the officer only in light of prevailing conditions of continuous rains in the area. But we hope the SIT will submit a better and comprehensive report next time," the bench said.
Earlier, during the hearing, the CBI, which is investigating the Narendra Dabholkar case, also submitted a progress report on its probe.
CBI counsel, Additional Solicitor General Anil Singh, told the court the agency was working on tracing the weapons used in the case and the exercise would take another four weeks.
The HC accepted the CBI's submissions and adjourned the hearing to next month.
Narendra Dabholkar was shot dead on August 20, 2013 in Pune while on his morning walk.
Govind Pansare was shot at on February 16, 2015 in Kolhapur and died of his injuries a few days later on February 20.