Deputy Andrew Lewis broke the States code of conduct, a panel has found.
He faced questioning from the Privileges and Procedures Committee yesterday, following accusations he had lied to the States while he was Home Affairs Minister in 2008, and later to the Jersey Care Inquiry.
In a statement, he said he had acted with "integrity and impartiality" and had "no intention to mislead".
The Privileges and Procedures Committee has since found he did break the code and say they will be producing a report within the next few days.
Deputy Lewis has temporarily stood down from his role as Chairman of the Public Accounts Committee but has denied any suggestion he lied.
In the Independent Jersey Care Inquiry report released last month, Frances Oldham QC said, "Andrew Lewis lied both to the States and to us".
The Deputy will not face criminal proceedings, due to immunity given to States Members when addressing the Assembly or an inquiry.
However, he could face sanctions by the Privileges and Procedures Committee.
The Committee is yet to confirm what, if any, action will be taken in light of their findings.