Executive Councillor Ip Kwok-him says the mystery surrounding the disappearance of bookseller Lee Bo, should now come to an end.
Ip told an RTHK radio programme that the bookseller himself had made it clear that he had gone to the mainland voluntarily to assist with an investigation.
He said those who don't believe that, will continue to do so.
A member of the National People's Congress Standing Committee, Rita Fan, echoed his view.
It was widely believed that Lee was spirited out of Hong Kong in December by mainland security agents because the titles his bookstore sold were critical of the central government.
He returned to the mainland yesterday, less than 24 hours after he had arrived back in Hong Kong.