Of course this actually is in the Bible. Biblically, the blood is seen as the seat of life, and it belongs to God and God alone. This is why, for example, Hebrews are not permitted to consume blood (e.g. Leviticus 17), and why the blood was so important in the sacrificial offerings. It is also why it is Abel's blood that "cries out to God from the ground." So in the Biblical sense it is precisely the spilling of human blood that is prohibited, and all exceptions are explicit (e.g. Genesis 9:6). It doesn't matter whether the blood one is spilling is their own or someone else's. Either way it belongs to God, and it is not permitted.
(As for the claim in post #21 that Saul's suicide reflects no judgment by the Biblical author, this is just an ignorant reading of the text and a failure to understand Hebrew literature.)