Numerous officers (at least 20 on the ground, plus two helicopters) executed a search warrant of a remote farm where a marijuana grow had been located. During the search, some of the officers found guns and broadcast this to other officers involved in the search.
While the search was going on, Purdue showed up. This particular location was apparently so remote that anyone driving down this particular roadway was obviously visiting it, so by virtue of the fact that he was there the police considered him a suspect (the courts were good with that). When Purdue got close enough to the property to see the police were already there, he turned around and took off. Some of the perimeter officers conducted a high risk stop, ordering Purdue and his girlfriend onto the ground at gunpoint. Purdue complied, although his girlfriend didn't because she was nine months pregnant.
During the high-risk stop, one of the officers asked Purdue some incriminating question about why he was there, whose marijuana it was, etc. Purdue made some incriminating statements (it was his grow, and he was there to check on it). To be clear: by "during the high-risk stop," I'm not saying that they cuffed Purdue up, stuffed him in a car, and started interrogating him. The officer asked him all of these questions whilst standing over him and holding him at gunpoint! And given that the prosecution didn't learn about this interrogation until the case went to court (leading to some discovery issues with this case), the officer probably neglected to mention any of this in his report. All around, this was incredibly sloppy work.
Anyway, Purdue made some incriminating statements. Then he and his girlfriend were ushered off to speak with some other investigator who read him his rights and continued interrogating him, along with a county attorney who was there for some reason. During the interrogation, they threatened to charge Purdue in federal court instead of state court if he didn't cooperate (and told him this would mean more jail time, and more time away from his unborn child). Purdue made a few more incriminating statements, but eventually decided that his smartest course of action was to STFU. So he invoked his right to remain silent.
Pretty impressive, that someone could go to all the trouble of getting a search warrant and then still screw up the case this badly, right? Anyway, this went to trial. The trial court held that all of Purdue's statements were admissible, and he was convicted. He appealed on several grounds. There was some courtroom procedural stuff and the aforementioned discovery issues, but I won't go into that too much. The important part for cops to know is that if someone confesses, you should probably include that information in your report. That way, the prosecution knows that it happened and they can disclose that information to the defense attorney (which they are required to do). And hopefully you can keep yourself out of the appellate courts that way. Purdue also argued that his statements should've been suppressed because they were involuntary, because they were in violation of Miranda.
In case I've put you to sleep, this is where it gets interesting again: the tenth circuit recognized that the police had reasonable suspicion to detain Purdue (based on his arrival at the premises where a search warrant was being executed, particularly in light of the fact that it was such an isolated location). Further, the court recognized that because of the firearms which had been discovered on the premises, it was reasonable for the police to fear that Purdue was armed and dangerous and to conduct a high risk stop. The court did point out that gunpointing suspects is a level of force more commonly associated with formal arrest, and that if it hadn't been for the discovery of the firearms then this level of force would have converted the Terry stop to an illegal arrest, but in light of the circumstances the police were behaving reasonably. So far, the police are in the clear.
But the court also recognized that being under arrest (for Fourth Amendment purposes) is not the same thing as being in custody (for Miranda purposes). Although stopping Purdue at gunpoint did not convert the stop to an arrest, the stop interfered with Purdue's freedom to the degree normally associated with a formal arrest, and for Miranda purposes he was very much in custody. So interrogating him without advising him of his rights was illegal (and asking him "what are you doing here?" qualified as an interrogation, as did asking him questions about the "stuff" he was there to check on and whose it was). Also, the court held that the statements he made while laying face down on the ground while an officer stood over him with a gun pointed at him were involuntary. Go figure.
Here's the way the court put it: "if police officers choose to use forceful methods to detain a suspect for investigation, they must back off before interrogating him."
As far as the second (post-Miranda) interrogation, the court held that this interrogation was so closely connected to the coercive pressures of the first one that the Miranda warnings weren't enough to save it. Essentially, everything in that interrogation was held to be involuntary and was suppressed.
Purdue's conviction was reversed, and the case was remanded for a new trial without Purdue's incriminating statements.