Having not conducted any real investigation into the novel (apart from a first reading) it does seem a little bit all over the place. but out teacher had given us prior warning that Anils ghost was sort of like a curve ball in the HSC, where we really have to apply what we know in determining whether it's crime fiction or not. I dont think there is a right or wrong answer, just as long as you can back up what ur saying.
Honestly, i think Ondaatje is an amazing writer, and as candypants said, is similar to Cedars . Both Guterson and Ondaatje write in a kind of poetic language (ondaatje is also an accomplished poet, as you have probly all researched) and his style is really amazing. I think it is still possible to determine that anils ghost is crime fiction if you look at the conventions being applied:
1. there IS a crime at it's heart (although sailors death perhaps serves as a microcosm for all the political killings and unexplained deaths in the war.
2. the detective DOES use rationality and deduction in solving the crime (Anil uses forensic medicene to determine where Sailor worked, his village, his job etc.)
3. there are significant values in the text (like i think gamini or Sarath says 'only our weapons are state-of-the-art')
4.there is a sense of disorder created and a feeling of catharsis or purgatory (wrong word? i dunno) at the end, which is perhaps the ending scene with Ananda rebuilding the buddha.
the real difference might be that the crime itself is not complete in the context, and the crime is used as a scaffolding (sorry, cliched statement) to explore literary values within the sri lankan society
i'm babbling....