Pursuant to section 31, criminal liability attaches to those who perpetrate a crime and extends to anyone who, with knowledge of the perpetrator's unlawful purpose and with the intent to facilitate that purpose, promotes, aids, or encourages the commission of the crime. (People v. Beeman (1984) 35 Cal. 3d 547, 554-555, 199 Cal. Rptr. 60, 674 P.2d 1318). The charged crime must be a "'natural and probable consequence' of some other criminal act that the defendant knowingly and intentionally aided and abetted. " (People v. Williams (1997) 16 Cal. 4th 635, 674, 941 P.2d 752). However, the defendant need not personally participate in the commission of a crime to be held liable as an aider and abettor. ( People v. Montoya (1994) 7 Cal. 4th 1027, 1039, 874 P.2d 903). Section 31 fixes responsibility on an aider and abettor for a crime personally committed by an accomplice. (People v. Walker (1976) 18 Cal. 3d 232, 241-242, 133 Cal. Rptr. 520, 555 P.2d 306). When enacting new statutes, the Legislature is deemed to know of existing laws. ( Munoz v. City of Palmdale (1999) 75 Cal. App. 4th 367, 372). Had the Legislature intended for section 667.61 to apply only to active participants it certainly could have written such language into the statute. It explicitly distinguished between a perpetrator and an aider and abettor in section 667.61, subdivision (e)(3) and (4). These respectively require that the "defendant personally inflicted great bodily injury to the victim . . ." and "personally used a dangerous deadly weapon or firearm in the commission of the present offense.. . ." ( 667.61, subd. (e)(3), (4), italics added). By including the term "personally" in subdivision (e)(3) and (4) the Legislature described conduct which a defendant must himself engage in before that portion of the sentencing scheme applies. (See, e.g., People v. Reed (1982) 135 Cal. App. 3d 149, 152-153, 185 Cal. Rptr. 169; People v. Manners (1986) 180 Cal. App. 3d 826, 831-832, 225 Cal. Rptr. 798). Its choice to use the word "personally" in those subdivisions necessarily exclude those who may have aided or abetted the principal in contrast with the remainder of the statute where the term "personally" is not used. the absence of the qualification "personally" in section 667.61, subdivision (a) thus reflects a legislative intent to extend the sentencing scheme to all aiders and abettors regardless of the degree of their involvement.