"The Microgram Bulletin" is a monthly web-based newsletter published by the Drug Enforcement Administration. The April 2005 edition has a short item about 17 bricks of cocaine that were intercepted by the DEA in Nogales, AZ. Upon inspection, agents discovered a surprise inside the cocaine:
[E]ach brick was also found to contain a second, internal brick, wrapped in brown tape and cellophane, which contained an unknown, compressed, tan colored powder. Analysis of the white powder confirmed 85 percent cocaine hydrochloride adulterated with caffeine, while analysis of the tan powder indicated a mixture of 72 percent heroin hydrochloride and 7.2 percent cocaine hydrochloride. This is the first submission of heroin mini-bricks inside cocaine bricks to the Laboratory.
The DEA believes the smugglers hid the heroin inside the coke to "deceive mid-level transporters, who charge higher rates for heroin shipments versus cocaine shipments."
Link (Thanks, Amy!)