"The principal issue at trial was the identity of the person who killed Colleen Richardson-Luciano. The suspects were two, both of whom had equivalent opportunity to do so. Michael Luciano was one. James Cooper was the other. Luciano said it was Cooper. And Cooper could not deny it because Luciano killed him about a day after Colleen had been stabbed to death.
"A person charged with the murder of another is entitled to adduce evidence in response to the charge that shows or tends to show that another person committed the murder: R. v. McMillan (1975), 7 O.R. (2d) 750 (C.A.), at p. 757, aff'd  2 S.C.R. 824; IA Wigmore on Evidence (Tillers Rev.) at para. 139, pp. 1723-724."
R. v. Luciano,  O.J. No. 399; 2011 ON.C. LEXIS 14996; 273 O.A.C. 273; 267 C.C.C. (3d) 16; 2011 ONCA 89 (Ontario Court of Appeal, Feb. 1, 2011).
The dynamic evidence page
Evidence marshaling software MarshalPlan
It's here: the law of evidence on Spindle Law.
See also this post and this post.