There is a new twist in an increasingly bizarre case involving an encounter between a prominent investment banker and the LAPD.

Brian Mulligan, a Deutsche Bank executive with ties to the television and movie industries, says he was the victim of an unprovoked attack by LAPD officers in May. He claims to have sustained a broken shoulder blade, 15 nasal fractures and facial lacerations from the beating.

The arrest report says that Mulligan admitted to using marijuana and ingesting bath salts four days before the encounter. Mulligan's lawyer said the allegations were made up by the LAPD to excuse what he called an "unmerciful beating." The charges against Mulligan have been dropped, but he pursued a lawsuit against the LAPD. The LAPD has launched a force investigation into Mulligan's charges and their defense may now hinge on the evidence found in an audiotape obtained by "CBS This Morning."

According to CBS News senior correspondent John Miller, the tape reveals an encounter between Mulligan and Glendale Police just two days before the LAPD scuffle. In the tape, Mulligan admits to being "a little paranoid" and later told the officers, "I will tell you what ... my lawyer will kill me ... I went to a head shop and I bought some of that white lightning stuff." He then admitted to snorting the "white lightning" up to 20 times.

White lightning is another name for bath salts, a commercial name for a synthetic drug that is similar to methamphetamine. The symptoms of methamphetamine use include paranoia, panic attacks and delusions, which, Miller says, could explain Mulligan's alleged behavior on the night of his run-in with the LAPD.

Miller also reported that the LAPD has received the tape and interviewed the Glendale police officer involved and are satisfied that the man in the tape is indeed Mulligan. Mulligan's lawyer had no comment on the tape. Miller added that Mulligan's case against the LAPD will go forward but that the audiotape evidence presents "a real credibility issue" for the LA-based banker.

Listen to the full audiotape from the Glendale police department below: