What is the test for using evidence of an uncharged crime to identify a perpetrator?

If evidence of an uncharged crime is used to establish the identity of the perpetrator, there must be common features shared between the charged offense and the uncharged misconduct which are sufficiently distinctive that they support the inference the same person committed both acts. "'The pattern and characteristics of the crimes must be so unusual and distinctive as to be like a signature.' [Citation.]" (People v. Ewoldt, supra, 7 Cal.4th at p. 403.)

In order to prove motive there must be a nexus or direct link between the prior crime and the current one, but it is not necessary to show that the crimes were similar. (People v. Scheer (1998) 68 Cal.App.4th 1009, 1018.).