I think you're too quick to dismiss the possibility. The point of parallel construction is that the police construct a plausible (and, more importantly, legal) means of finding the evidence that they used in an investigation that masks its true, illegal origin. More importantly, unlike false flags -- where the only "evidence" for their use is the ravings of conspiracy theorists and some internal suggestions by government officials in the 60's -- parallel construction is a technique that we know the government uses by their own admission.

From Reuters (http://www.reuters.com/article/2013/08/05/us-dea-sod-idUSBRE...):

> The undated documents show that federal agents are trained to "recreate" the investigative trail to effectively cover up where the information originated, a practice that some experts say violates a defendant's Constitutional right to a fair trial. [...]

> After an arrest was made, agents then pretended that their investigation began with the traffic stop, not with the SOD tip, the former agent said. The training document reviewed by Reuters refers to this process as "parallel construction."

> The two senior DEA officials, who spoke on behalf of the agency but only on condition of anonymity, said the process is kept secret to protect sources and investigative methods. "Parallel construction is a law enforcement technique we use every day," one official said. "It's decades old, a bedrock concept."

> A dozen current or former federal agents interviewed by Reuters confirmed they had used parallel construction during their careers. Most defended the practice; some said they understood why those outside law enforcement might be concerned.

> "It's just like laundering money - you work it backwards to make it clean," said Finn Selander, a DEA agent from 1991 to 2008 and now a member of a group called Law Enforcement Against Prohibition, which advocates legalizing and regulating narcotics.

Given how they talk about parallel construction, it certainly sounds like it's not an uncommon technique, so do you think it's so implausible? I'm not going to say they did or didn't use it, because the simple fact is that I don't know, but given that "Parallel construction is a law enforcement technique we use every day" that is "decades old, a bedrock concept," it doesn't seem too implausible that they would use it in such a high profile and important case.