People v. Butte CA1/5, A157561

In Aug. 2017 defendant William Butte posted a Craigslist ad seeking a "naughty little girl"; an undercover DA investigator (posing as a 15-year-old "Lizzy") responded via the KIK app.
The chat shows Butte (identifying himself as 48) asking graphic sexual questions, instructing the purported minor about pornography, arranging a meet at Starbucks, and sending/agreeing to buy two drinks.
Officers arrested Butte at the meeting location, seized his phone, and recovered the KIK messages; Butte admitted posting the ad and engaging in the sexualized exchanges, saying his motive was "curiosity."
At trial Butte claimed he sought role-play/chatting with adults pretending to be minors and denied intent to have sex with a real minor.
Jury convicted him of meeting a minor for lewd purposes (Pen. Code § 288.4(b)), attempting a lewd act on a child (Pen. Code §§ 664, 288(c)(1)), and sending harmful matter to a minor (Pen. Code § 288.2(a)(1)); court sentenced him to 5 years probation with one year county jail and sex-offender registration.
On appeal Butte challenged (1) prosecutorial misconduct in opening statement (labeling him a "pedophile") and (2) the exclusion of defense expert Prof. Jeffrey Hancock on online-communications analysis; the Court of Appeal affirmed.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Prosecutorial misconduct for calling defendant a "pedophile" in opening	The prosecutor's characterization was supported by evidence of defendant's sexualized conduct toward an apparent minor and was a proper rhetorical opening	The label was prejudicial, argumentative, and unsupported ("pedophile" implies sexual attraction to prepubescent children) and warranted reversal	No prejudicial misconduct: multiple reasonable meanings of "pedophile," context pointed to sexual attraction to children generally, evidence supported the label, and jury was instructed statements are not evidence; conviction stands
Exclusion of defense expert (Hancock) on online-communications/age inference	Expert admissible to show that a reasonable reader would suspect the purported minor was not 15; methodology grounded in published research and automated linguistic analysis	Trial court erred in gatekeeping and prevented defense from establishing reliability; testimony would have assisted jury on intent/knowledge	No abuse of discretion: court held a §402 hearing, found Hancock failed to show general acceptance or sufficient validation under Kelly, and some proposed opinions were within jurors' common experience; exclusion affirmed

People v. Flores, 9 Cal.5th 371 (Cal. 2020) (constitutional and state-law standards for prosecutorial misconduct)
People v. Bennett, 45 Cal.4th 577 (Cal. 2009) (standard of review and prejudice analysis for prosecutorial misconduct)
People v. Kelly, 17 Cal.3d 24 (Cal. 1976) (foundational reliability requirements for expert testimony of novel scientific techniques)
People v. Peterson, 10 Cal.5th 409 (Cal. 2020) (application of Kelly to novel techniques and reliability showing)
Sargon Enterprises, Inc. v. Univ. of S. Cal., 55 Cal.4th 747 (Cal. 2012) (standard of review for admissibility of expert opinion)
People v. McWhorter, 47 Cal.4th 318 (Cal. 2009) (upholding exclusion where expert failed to identify or validate technical methodology)