I would be skeptical of the objectivity of this given the time period, as well as the quality of the LSD. Mid 70s had a lot of homebrew drugs going on, and cutting and mixing were just ramping up.

In addition to testing of their stomach contents, urine, and blood (pp184-185), "A white flaky material (208mg) was confiscated by police and identified as the large quantity of powder used at the party. Analysis by thin layer chromatography, fluorescent analysis, mass spectrography and the melting point and mix melting point identified this substance as almost pure (80 to 90 percent) D-lysergic acid diethylamide tartrate." p185.