The bigamist doesn't not tell the authorities in the jurisdiction of the subsequent marriage that he/she is previously married. If he/she and maintains the secret from authorities until AFTER a later divorce, then there will be a record of a divorce for a marriage that never legally existed.
INS staffers and the U of HI staffers suspected bigamy but didn't report it to HI authorities, it would appear, especially since BHO Sr. was lying about Kenyan law and claiming he was divorced from Kezia under an alleged tribal custom of verbal divorce. Being so far removed from Kenya they may have regarded it as impractical to investigate bigamy, unless that became necessary if permanent US residency was sought based on the marriage.
In case you haven’t seen this Seize, Brown Deer posted this link tonight of Corsi going over Obama Sr. INS documents.
“Obama’s INS Birth Documents
Published on Jul 12, 2012 by DrJeromeCorsi
INS Birth Documents Cast Doubt On Kenyan Being Biological Father”
19:58 min video.
http://www.youtube.com/watch?v=nHlWn6nUE9E&feature=youtu.be