Post-Offence Conduct. R. v. Gough
In R. v. Gough (Ont CA, 2020) the Court of Appeal comments on the admission of evidence of 'post-incident' conduct (aka post-offense conduct):
 In cases where evidence of post-incident conduct is tendered to prove an essential element of the Crown’s case, its admission is governed by general evidentiary principles. The evidence must be relevant to a material issue at trial. It must be admissible. And its probative value must outweigh its prejudicial effects: R. v. Adan, 2019 ONCA 709, at para. 65.. R v Kler
 Determining the relevance of post-incident conduct evidence “is necessarily a case-by-case, ‘fact-driven exercise’”: R. v. Calnen, 2019 SCC 6,  1 S.C.R. 301, at para. 108, per Martin J. (dissenting, but not on this point). In some cases, this evidence may be relevant to the issue of intent and to distinguish between different levels of culpability: Calnen, at para. 119, per Martin J. (dissenting, but not on this point). In others, it may be used to prove that a murder was planned and deliberate: R. v. MacKinnon (1999), 1999 CanLII 1723 (ON CA), 132 C.C.C. (3d) 545 (Ont. C.A.), at paras. 14-15; R. v. Poitras (2002), 2002 CanLII 23583 (ON CA), 57 O.R. (3d) 538 (C.A.), at para. 11; R. v. Azzam, 2008 ONCA 467, 91 O.R. (3d) 335, at paras. 46, 49; and R. v. Khan, 2007 ONCA 779, 230 O.A.C. 174, at para. 5.
 Despite its reception, evidence of post-incident conduct may pose unique reasoning risks. The separation in time of the events which form the subject-matter of the charge may make it more difficult to ground the inference that the murder was planned and deliberate. The evidence may have a veneer of cogency disproportionate to its true probative value. It may spur speculation, spawn imprecise reasoning and encourage decision makers, such as an untutored jury, to jump to dubious conclusions: Calnen, at para. 116, per Martin J. (dissenting, but not on this point).
In R v Kler (Ont CA, 2017) the Court of Appeal clarifies that the law does not take a categorical approach to post-offence conduct, it's evidentiary treatment all depends on the nature of the conduct:
 Whether the descriptive used is post-offence conduct or after-the-fact conduct, the designation tells us that what is involved is evidence of things done or said after an offence has been committed: not before and not at the same time, but after. This is circumstantial evidence to which no special rule attaches: R. v. White, 2011 SCC 13 (CanLII),  1 S.C.R. 433, at paras. 31, 105, 185.
 As with circumstantial evidence generally, jury instructions about the use of evidence of post-offence conduct must not invite the jury to apply the criminal standard of proof to the individual items of evidence: R. v. White, 1998 CanLII 789 (SCC),  2 S.C.R. 72, at paras. 42-49.
 The courts eschew a list or category approach to determine whether things done or said after an offence has been committed may be relied upon as evidence of post-offence conduct. It all comes down to relevance. Examples of relevant evidence abound, among them, evidence than an accused destroyed or attempted to destroy objects that tended to link him or her to the commission of the offence charged. See e.g. R. v. Vant, 2015 ONCA 481 (CanLII), 324 C.C.C. (3d) 109, at para. 129.