Holding placards, with photos of the mutilated body of the YC activist, they trooped to the Well of the House and placed a banner in front of Speaker P Sreeramakrishnan's podium, forcing an early adjournment of the House.
Earlier, the Question Hour was also suspended following the opposition's protest.
During the Zero Hour, the opposition took up the issue as an adjournment motion and said the family of the slain YC worker had no trust in the ongoing investigation by the state police.
Replying to the notice of the motion, moved by Sunny Joseph (Congress) on the issue, Vijayan rejected the demand for a CBI probe and said the state police was conducting an efficient, impartial and scientific inquiry.
Five persons were already arrested and if any more were involved, they would also be brought to book, the chief minister said, adding that the conspiracy angle would also be probed by invoking section 120(b), IPC (criminal conspiracy).
"The investigation by the state police is going on in the right direction. So, there is no need for a CBI probe," he said.
Stating that Shuhaib's killing was "highly condemnable", the chief minister said it could not be justified in any manner.
He added that the state government was of the view that individual and ideological differences should not lead to violence.
Vijayan also made it clear that the CPI(M)-led LDF government would initiate stringent action against the perpetrators of political violence, whoever they might be.
He also rejected the opposition's allegation that political violence had increased in the state after the LDF government came to power in May, 2016.
Taking a dig at the Congress for claiming that they never indulged in violence, Vijayan listed out various incidents of political violence and killings in Kannur, in which Congress workers were allegedly involved.
Turning the table at senior Congress leader K Sudhakaran, who is staging a hunger strike in Kannur demanding a CBI probe into Shuhaib's killing, Vijayan said he (Sudhakaran) himself was an "instigator of violence" when he was the president of the Congress' Kannur district unit.
However, Leader of Opposition Ramesh Chennithala maintained that the government and police were not sincere in arresting the "real" culprits behind the crime.
Alleging that local CPI(M) leaders in Kannur had a role in Shuhaib's killing, he said not only those directly involved in the crime, but the conspirators should also be brought to book.
The Congress leader wanted to know why the government was shying away from ordering a CBI probe into the case and charged that efforts were on to mislead the police investigation.
The opposition would pursue the legal options if the government did not concede to the demand, he added.
Meanwhile, the fast by senior Congress leader and former MP K Sudhakaran and Youth Congress leader Dean Kuriakose, in Kannur and in front of the Secretariat here respectively, entered the eighth day today.
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