Immigration authority can look through convictions for inchoate offenses to determine if the underlying charged conduct bars withholding of removal.
Statutory list of documents that establish conviction for a predicate offense is not an exhaustive list of the manner in which the predicate offense can be proved.
Administrative challenge that the petitioner's conviction was not established by the statutory list does not appropriately exhaust a claim that the predicate conviction does not justify a withholding of removal.
http://www.ca4.uscourts.gov/opinions/171213.P.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.