Unlike in most other European countries, Dutch law allows for life imprisonment without parole, from which only a royal pardon can save you. Since 1970, 43 people have been convicted, 2 of whom were eventually pardoned, both because of terminal illness. A quick glance through the recent list of convictions[1] shows that most life sentences were imposed in cases of multiple homicide, homicide for financial gain and homicide related to organized crime.
In addition, convicts may be involuntarily committed when their sentence is over (and often before). This is aimed at rehabilitation, but can be extended indefinitely.
OK, thank you. So I will not tell anybody that I did that by request of someone else, then serve 12 years and will be free and with money, unless my mother will come in: https://en.wikipedia.org/wiki/Ram%C3%B3n_Mercader (in English).
It's just example. People are killing people for way smaller reasons. My price is very high, isn't?
How much people live in Dutch? If Russians will send one killer for every key men in country, country will be their in just 12 years, while they lose nothing, because Dutch prison is much much more comfortable than a flat in Rostov. I see that in Ukraine right now.
In addition, convicts may be involuntarily committed when their sentence is over (and often before). This is aimed at rehabilitation, but can be extended indefinitely.
[1] https://nl.wikipedia.org/wiki/Lijst_van_tot_levenslang_veroo... (in Dutch)