King Gyanendra of Nepal has failed to meet a deadline to answer questions about his role in the crackdown against pro-democracy protesters this year.
Troops and police are accused of excessive force
The monarch headed the cabinet before the popular uprising forced him to end his year-long direct rule in April.
It is the first time a Nepalese king's decision had been publicly questioned. The palace has given no reason for the king's failure to respond.
Twenty-one people died in the crackdown on the huge pro-democracy crowds.
Several hundred more were wounded as security forces used batons, fired tear-gas shells and opened fire to disperse protesters.
'Above the law'
Panel member Harihar Birah said that the king had been asked to give his answers in writing by Wednesday.
He said the panel would still present its report to the government.
The king faced strong opposition to his coup
"We [the commission] waited the whole day today but received no statement from the king," he said.
"So we will carry out our investigation on the king for his role in the suppression of the April movement... depending on other evidence collected from various people."
He said that the commission had wanted to give the king a "chance to clarify whether the allegation that he was responsible for the crackdown was justifiable or not".
The BBC's Sushil Sharma in Kathmandu says that the king has traditionally been above the law.
But the monarch's position has been weakened after the uprising against his direct rule.
The future of the monarchy is currently being debated in peace talks between a multi-party government and Maoist rebels.
Restoration of democracy
The panel, which has been investigating alleged excesses against pro-democracy demonstrations in April, has questioned more than 200 officials - including former ministers and the chiefs of the security agencies - since it was formed in June.
The authorities say that it will recommend action against any officials found guilty of committing excesses.
A retired supreme court justice, Krishna Jung Rayamajhi, heads the five-member panel.
Hundreds of thousands of people took to the streets across the country to press for the restoration of democracy during three weeks of protests that forced King Gyanendra to end his direct rule.
A multi-party government has been in place since then.
The five-member commission has set 27 October as the deadline to wrap up its six-month-long probe.
It has collected 610 different cases of alleged repression during the April unrest.
It has also recorded statements from 61 people injured during the uprising.
Commission officials are planning to go to an isolated place outside Kathmandu to finalise their report and recommendations.