To assure himself of this, he poses as a Roman Catholic priest in order to meet Nina while she is held pending her bail appearance. Finding her wearing a crucifix necklace (which would be forbidden in her communist homeland), he thinks she's innocent when she does not confess to the murder.
To confirm his suspicions, he disguises himself as a Roman Catholic priest to encounter Nina while she is being detained before her court appearance. Upon seeing her wearing a crucifix necklace, which would be prohibited in her communist country, he assumes she's innocent when she doesn't confess to the crime.