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TMZ is claiming that pop star Michael Jackson was using multiple aliases in order to obtain his prescription medications.

The website alleges that Jackson often used the names Jack London and Omar Arnold in order to get a hold of such drugs as Demerol. Additionally, he employed the use of the name of his office manager and bodyguard.

These inconsistencies have sparked an investigation by the federal Drug Enforcement Administration in coordination with the Los Angeles Police Department as part of ongoing information gathering surrounding the death of Michael Jackson.

Gallery Info: Michael Jackson file photos.