(a) Notwithstanding the provisions of section 604 of this title, any person, being at least 18 years of age, who knowingly uses, solicits, directs, hires, or employs a person 17 years of age or younger to violate any section of chapter 29 of this title, and is found to have violated this section is guilty of a crime and shall be sentenced to an additional term not to exceed 15 years which shall include the imposition of a minimum term which shall be fixed at one-third of the sentence imposed, during which the defendant shall be ineligible for parole. The court may also impose a fine not to exceed $300,000 or five times the street value of the controlled substance or controlled substance analog involved, whichever is greater.
(b) It shall be no defense to a prosecution under this section that the person mistakenly believed that the person who was used, solicited, directed, hired, or employed was 18 years or older, even if such mistaken belief was reasonable.
(c) Nothing in this section shall be construed to preclude or limit a prosecution or conviction for a violation of any other offense defined in this chapter or any provision of law governing one person's liability for the conduct of another, and a conviction arising under this section shall not merge with a conviction for a violation of the provisions of this chapter.