31 "Evidence may be authenticated by direct or circumstantial evidence, including its '[a]ppearance, contents, substance, internal patterns, or other distinctive characteristics.'" Commonwealth v. Purdy, 459 Mass. 442, 447-448 (2011), quoting Mass. G. Evid. § 901(b)(4) (2013). The voir dire of Colton presented sufficient evidence that some of the e-mails sent to Colton were authored by Gail given the long-standing relationship between Colton and the defendants, the defendants' prior use of the e-mail address at the time of the scheme, and the referencing of the harassing acts in the e-mails.17 7. Closing argument. In summarizing the evidence for the jury, the prosecutor stated: "Now, how in the world can the Johnsons explain to you why . . . ." William argues on appeal that this statement could be interpreted as a comment on the defendants' failure to take the stand. Viewed in context, the prosecutor's rhetorical question was merely an attempt to illustrate the point that the defendants' conduct could not be reconciled with their defense. It was a "fair, unemotional response to defense counsel's argument," grounded in both the 17 These electronic mail messages (e-mails) (in addition to telephone conversations between Gail and Colton) were also sufficient to establish that Gail knowingly participated in the harassing conduct with the same malicious intent as her husband. Accordingly, the evidence of Gail's involvement as a joint venturer in the scheme was sufficient to survive a motion for a required finding of not guilty. The judge's ruling to this effect was not in error.