i think fingerprints it's not that secure, it can be repliacated easily, by using the victim fingerprint, on any material that he/she may have touched, it's better to do it in another way like retina yes, or particolare code done with some gestures?

It isn't secure. I generally only use it on phones that don't have any sensitive data nor amount of money on them. People leave their fingerprints pretty much everywhere, one would just need to keep watch of where you're going for a few days and would surely be able to reconstruct your fingerprint from some public place (e.g. transport, coffee shop). Additionally, the law enforcement can unlock your device (or gain access to your money in this case) when we are talking about a fingerprint. When we are talking about passwords, they can't force you to give it to them. Depending on the complexity, they may not be able to do anything about it.