There are two year olds who do not speak?
Anyway, in one of the most written about crimes in Swedish history, the
Catrine da Costa murder, one of the key witnesses in the ultimately unsuccessful trials of the two main suspects was a baby girl who was 17 months at that time. Of course, witness reports of such a young child needs to be processed by child psychology experts, and is still incredibly vulnerable to a number of bias issues. So, naturally, the testimony is of limited value. But I think saying the testimony is close to useless is stretching things way too far.