A Catholic priest in good standing would not marry a couple without all of the proper permissions and paperwork, including a declaration of nullity from a prior bond.
Therefore, what you can conclude is that this person is either (a) not a validly ordained priest, Catholic or otherwise, and never has been or (b) a validly ordained priest that has been excommunicated, laicized, or otherwise expelled from the Catholic Church or © someone validly ordained in some schismatic group that has never been a Catholic.
There are many groups out there that advertise “catholic weddings” for anyone who wants one. For example, this group that calls themselves “monks” and advertise “catholic” weddings. They also advertise their marriages are sacraments. These marriages are INVALID.
A Catholic who approaches such a person does not validly contract a marriage in the Catholic form.
It means your friends are not validly married and have committed a serious sin. They are living in a state of adultery if the facts are as you describe them.
They need to go talk to their priest ASAP. There is no way to short cut, circumvent, or otherwise get around the need for a delcaration of nullity before attempting a marriage. There is also no short cut, circumventing, or otherwise getting around the need to contract a marriage in the Catholic form.