In some US states, a crime of passion is a legitimate legal defense.
Moreso than ever though, since it is a jury system. Sympathizing with victims of abuse is a common occurrence.
I'd say, hey, it's probably culture shifting and legal defenses are a direct reflection of changing cultural values.
You know, from, "I killed my husband because he was a cheatin on me."
To... "I killed my girlfriend because she was being abusive towards me for years, and I snapped."
We could probably drag feminism into this one as well. Okay, I'll be fair. We could probably scrutinize gender issues on this one.
How does one get away with Murder in your view?
Invite someone away on vacation, liquidate your assets, and never come back.
If someone would suspect something, then a short trip to the country side, and some concrete will do just fine.
In other words. I don't live in the delusional televison high tech detective world the rest of you do watching prime time safety tv.
Missing people is the real statistic. Murders are not down. They are way way up.
It is only guess. Here are some random statistics. Japan.
http://www8.cao.go.jp/koutu/taisaku/19html/tswp2005web.html
The USA.
http://www.crimelibrary.com/criminal_mind/forensics/americas_missing/2.html
Reports of missing persons have increased sixfold in the past 25 years, from roughly 150,000 in 1980 to about 900,000 this year. The increase was driven in part by the country's growing population. But the numbers also indicate that law enforcement treats the cases more seriously now, including those of marginalized citizens.
If that sort of stuff interests you, I highly suggest you start searching real estate professionals and missing peoples.