How long will the blood DNA remain on a knife?

[Repiter]

DNA can be extracted from even very tiny samples long after the knife cuts someone. If blood dries on the knife, it will be available to analyze for years.
Even tiny bits of blood or tissue that get into the cracks and crevices of knives can be extracted and provide a match.

[Huera]

I recently came across a very interesting company on the Internet that has been working in the field of blood research for many years. They are engaged in blood dna extraction and I really liked the scientific work in this topic. If you need to take a blood test or come for a DNA or RNA test, I advise you to contact them because they are specialists in this regard.

[JaceKristopher]

Why is there blood on the knife in the first place? I even read about a bloody knife on https://www.collegebasics.com/blog/h...-amazing-tips/. It was an ad, not sure what it was about though.