I struggle with that. I would assume (and it can be a big assumption) that LE has more knowledge than has been made public, and some things involved may just take more time than we would like. I think most people get the idea that crimes are solved quickly because we see hour-long, fictionalized tv shows that have instant test results, instant this, instant that, etc. But in real life it can take a lot of old fashioned detective work, paper work, interviewing, etc.
LE also will want to keep some info under wraps to the public so suspects can be questioned about details that only he would know (that were not common knowledge) or in some cases to protect the family (in cases of sexual assault, sensationalized stuff etc).
The other big case I followed closely was like this. When the story broke it was HUGE. National news. Wild rumors. Only the bare bones of the story were made available by LE. A lot of what was stated did not make sense or seemed to contradict itself. After a couple weeks, the case went COLD as far as news and media went. NOTHING. Not a peep. Just rumors, more rumors, bizarre rumors, blah blah blah. Then, out of the blue (as far as the public was concerned), about one month after the crime, LE announced they had a suspect named, they put out a BOLO for him, and he was arrested that night.
I think in this case the lack of ANY news, details, statements is starting to have a negative effect on the case as far as public support goes. People have been busting their butts for over a week with NOTHING. Hope and faith and prayer will only go so far before the realities of life set in and folks settle back into their old daily routines. If LE needs public support they must find a way to keep the public's interest and focus levels up.