>it never really explain on WHY he was obsessed...i could
>understand the cop's particular obsession, but not the lead
>character...they DID show him getting closure in the end, and
>him reuniting with his wife & kids, but it never explained WHY
>he was obsessed when he had absolutely no connection with the
>case...he was a sidebar

He said he was obsessed with puzzles. It only seems natural he'd become completley obsessed with one that started out slow/easy enough (the ciphers) - he stayed in those meetings with the rest of the newspaper staff with no real reason to because there was a problem that needed to be solved in the form of a type of riddle. That evolved into a much more difficult puzzle that he NEEDED to solve. Once he finally did he could move on.