This article has nothing to do with Michelle's murder however, this is an interesting article about a warrant which has recently been unsealed. It seems to me the main reason it was sealed was to hide a specific piece of evidence found on the body of this woman's charred remains.
http://www.wral.com/news/local/story/2481836/
"What the warrants do not disclose, however, is how Vanlata Patel died or a motive for her death. But they do indicate that during the Jan. 23 search, police were looking for yellow rope or twine as well as gasoline or any other substance that could have used to start a fire."
I can understand why they wanted this fact hidden - in talking to the suspect they could basically lead or mislead him about this aspect. It is possible the same applies in these recent warrants served on jy and his family.