Steve, I understand your point, but I think that "mkr" was making a simple spelling error. After all, vowel sounds in English are weak when compared to the vowel sounds in other languages; it's easy to confuse vowel sounds when writing English.
The English word, homocide, is based on the Latin - homo [which means "man"], and cidere [which means "murder" or "slay"]. The word, homosexual, is based on the Greek prefix, homo, which means "[the] same."
Just to reiterate my previous point, I think that, for the most part, people who write homocide instead of homicide are usually making a simple spelling error. It's very easy to make spelling errors in English.