In such a case, it is possible that the perpetrator had planned their activities wisely. They may have used protection on their hands, for example, high quality gloves that do not allow for fingerprints to be left on the weapon. In typical cases, fingerprints are left on a weapon even when using surgical gloves that cling tightly to the hand. It is also possible that the murderer used another weapon to commit the offense and left with it. Another possibility is that the material used to make the weapon is one that does not retain prints. At times the prints may be too faint for proper identification. Fortunately, fingerprints can be collected from the surfaces in the scene of the crime. Glass, for example, retains prints that are highly detectable especially if the hands of the perpetrator were wet, bloody or greasy. On the hand, lean surfaces are more likely to retain fingerprints compared to dirty ones as the dirt may inhibit latent prints from being visible on the weapon.
A case like this may mean that a different person committed the crime. It may also be that another person touched the weapon with bare hands after the murder, for example, an investigator hence interfering with the evidence. It may also be that the perpetrator used the weapon that had previously been touched by another person and used material that does not allow their prints to be left on the weapon. There may also be the possibility that a different person touched the weapon leaving their prints but the murder used a soiled hand on the weapon thus inhibiting the formation of their fingerprints.
Such a situation is tricky and may mean different things. While it is possible for the suspect to be guilty, it is not always so. In some cases, the prints ay offer direct evidence that the suspect was responsible for the murder.