Sure. First, let me point out that a house that size would have hundreds of samples to go through. There are several steps in the process. It's not possible, aside from blood or semen, to know where exactly DNA will be found - so lots of swabs. Here are the national stats:
Now, if your question is why, in a nation like the US, it could take this long for most places to process lab materials, the answer to that is money. That, and a lack of qualified people to run those labs. Where I live, there are people older than me putting in "just a few more months" before they retire - while their labs wait to find new hires. There aren't many. So it's not just money - but if they made the jobs pay more, I suppose eventually they'd have more recruits. They pay around $100,000 a year here for an experienced tech - which is considered "not enough" by my students looking for a program of study. Naturally, it takes a degree in science - preferably genetics or genetic anthropology.
Take a look at Idaho. Homicide - rush situation - is 45-60 days. And that's for each stage of this analysis. First, there would be the separation of organic particles from inorganic - with carpet fibers, clothing fibers, etc, going off for further analysis in another pace, and the biologic evidence going on for separate DNA analysis. Typically, one would want a cluster of various blood cells and samples from the autopsy. But for touch DNA, they'd need to include other detectable bits of DNA from swabs - all the swabs have to be analyzed - but only some will have DNA.
So for the two stages to take place and the touch DNA to be isolated and sent to yet another specialist, it would be 90-120 days (from receipt of samples, so let's say 7 days after the murders). I doubt they'll release any final autopsy report until all of this is done.
Since the DNA of the victims is only being used for ruling out who the perp is, that's likely been done. But now - they'll process certain swabs/samples first (getting stranger DNA from a pool of blood is not guaranteed to work - part of it will be luck). A well prepared killer would leave very little touch DNA. The DNA from all around the house (door jambs, door knobs, faucets, etc) will likely turn up dozens of partial profiles.
The sorting of partial profiles into meaningful perp data may or may not work and can take months. They would have little bits of a strand that we can picture as string - a piece of string that would reach to the moon and back 150,000 times. Almost none of it is useful for the task at hand - just little areas that contain SNP's (markers unique to families, lineages and sometimes, individuals).
If they get lucky and do have, say, spit from the perp or the perp cut himself or lost a glove, they can move on to trying to find him through genealogical DNA analysis in as early as 6 months, maybe even less. If they think they know who he is, then they'll be trying to get trace DNA from him by the usual investigative means.
I am guessing that within just the bedroom zone of the two rooms, they're going to find DNA profiles of more than 2 people.
Did you know that even washing, with bleach, does not destroy all the DNA in underwear? And that women's underwear has been used to track their killers or to create a list of possible suspects? So the forensic vacuum contents could contain lots and lots of profiles - including people who lived in the house a year or more before. It's kind of a forensic nightmare.
People are used to saying that "rapid DNA results" occur - yes, they do. If you give an actual cheek swab and it goes directly into lab solution. Can be overnight, if the tech is available. But the murderer isn't going to give that kind of sample - and the victims' blood types and DNA are already known (and only useful to exclude stranger DNA, really).
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