(a) Upon the trial of any criminal action, or preliminary proceeding in a criminal action, arising out of acts alleged to have been committed by any person in violation of subsection (a) of section 493 of this chapter while under the influence of an intoxicating liquor, the results of any chemical test or tests administered in accordance with the provisions of section 493c of this chapter shall be admissible into evidence when otherwise admissible, and the amount of alcohol in the person's blood at the time alleged as shown by chemical analysis of the person's breath, blood or urine, shall give rise to the following presumptions:
(1) If there was at that time 0.05 percent or less by weight of alcohol in the person's blood, it shall be presumed that the person was not under the influence of an intoxicating liquor.
(2) If there was at that time in excess of 0.05 percent but less than 0.08 percent by weight of alcohol in the person's blood, that fact shall not give rise to any presumption that the person was or was not under the influence of an intoxicating liquor, but that fact may be considered with other competent evidence in determining whether the person was under the influence of an intoxicating liquor at the time of the alleged violation.
(3) If there was at that time 0.10 percent or more by weight of alcohol in the person's blood, that fact shall be prima facie evidence that the person was under the influence of an intoxicating liquor.
(b) The provisions of subsection (a) hereof shall not be construed as limiting the introduction of any other competent evidence bearing upon the question whether the person was under the influence of an intoxicating liquor or a controlled substance.