This is purely hypothetical. I am expecting a friend to call me and fess up to a serious crime. I am not a cop, and I have not gotten permission to record the phone call. (If I told my friend I was going to record the call he would obviously become very suspicious.) He calls me, I record the call, and he confesses to killing his ex-girlfriend. He provides me with details of how he did it. Details that only the killer would know. I contact the detective in charge of the investigation and provide him with the recording.
Of course, none of this is admissible in court since I didn’t get permission to record the call, but can the police use the information my friend provided me to look for other evidence that points to my friend, and would that be admissible in court? Pick any jurisdiction you like.
Yes, the police can use tips from an informant to open an investigation. They would have to develop admissible evidence on their own to get a proper arrest warrant.
The recording doesn’t have a ton of value due to the chain of custody and other issues–but you telling a cop “my friend said he murdered someone”, is entirely valid grounds for police to arrest someone for murder. It probably isn’t enough for a conviction by itself, but it’s a good start. You are evidence in this case because of what you heard, and could be called on to testify “yes, Jimmy told me he murdered Jack.” What generally wouldn’t be admissible would be an improperly acquired piece of evidence, or you testifying that “my friend Jill told me that Jimmy admitted he killed Jack.”
Let’s say I live in a single-party-consent-state, which I do. Does that change whether a confession made by someone over the phone would be admissible in court?
IANAL, but I’m sure there are a lot of good arguments that a competent defense attorney could use to try and keep it inadmissible, just as the prosecutors would try and keep it in. Ultimately, the judge would decide.
Is this research for a book, or do you actually suspect one of your friends or family members of nefarious doings?
My understanding is that a citizen that is not a part of law enforcement may break laws in order to obtain evidence that is now admissible. That citizen may face prosecution for the laws that they broke, but the evidence is still good.
Let’s say you break into your neighbor’s house to steal his TV. While you are in there, he murders his wife, and you have that recorded on your phone. IANAL, but my understanding is that that would be perfectly admissible evidence, even if you were breaking the law when you obtained it.
I think this alone would be enough for the prosecution. The recording would be handy, but if you reported that your friend confessed and gave you these specific details, the cops could use that to build a case. You would be called in as a witness and the court would have to figure out that you’re credible, but your statement that your friend told you he did it and gave you specific details would typically be enough on its own. Whether you got the details on a recorded phone call or while having a conversation while walking through a park shouldn’t matter all that much. The fact that you can provide details that only the killer knows means that you got the information from the killer somehow. I doubt if the cops would blow you off if you gave details but didn’t have a recording.
As a comparison, if an accused makes a confession to a cell mate while waiting trial, the cell mate can give that info to the prosecution and testify against that person. It doesn’t matter that there is no recording of the confession made in the prison cell.
The recording might be more critical if there weren’t specific details. If he said “I killed her” but didn’t give any specifics, then that would be much better with a recording. Without killer-only details, there’s no way to know if you are just making up that he said he killed her or if he really said he killed her.