Three persons were arrested yesterday in connection with the theft last week of Nobel medal replica and other valuables from the child rights activist's Kalkaji residence.
While other stolen items, including the medal replica, have been recovered, the citation has not been found yet. The accused are claiming they had not taken away the citation, police said.
"They are claiming that they haven't stolen the citation.
But we suspect that they don't remember what they have done with it. We have shown them pictures but they haven't been able to recall about the citation," said a senior police officer.
Police are suspecting that after the accused decamped with items from three houses they burgled into including Mr Satyarthi's, they separated the loot that could be sold and those that were of "no use" to them.
"We are questioning them and are also trying to retrace the events that might have unfolded that night. The routes they might have used for commuting are also being studied to see whether they might have dumped the citation there," he said.
While Mr Satyarthi thanked Delhi Police for its speedy probe and recovery of the Nobel replica, he had said he is hopeful the citation too would be recovered soon.
"My sense is that for the thieves, the citation was just a piece of paper and they might have thrown it somewhere," he added.
"I have complete faith in the government, the police and the people of this great nation. I hope the Nobel citation is recovered soon. Nothing can deter my mission to work towards my children," he added.
The child rights activist won the Nobel Peace Prize in 2014. He shared the prize with Pakistan's Malala Yousafzai.
Mr Satyarthi had presented his Nobel Peace Prize medal to President Pranab Mukherjee in January, 2015. The original medal has been preserved and is now on display at the Rashtrapati Bhavan Museum.