I watched episodes 1 and 2 of the Secrets and Lies tv show.
so, this guy finds a (very recently) dead body on his morning run in the woods and then starts answering questions from a detective – where was he last night, did he move the body, why did he go for a run that morning, etc
the detective even starts tripping him up on the details. did he get home at 2am or 3am – which was it? did he have a couple drinks like he said he wanted to run off, or more?
he goes along with all this, is helpful and tells her stuff, and then is taken off guard that he’s a suspect. he needs a lawyer to advise him to stop volunteering help and instead tread carefully.
people are very naive about this stuff. DON’T TALK TO THE COPS, YOU WILL NOT BENEFIT. and if you find a body or were near a crime, YOU ARE A SUSPECT.
and lots of people are bad at their jobs, incompetent, stupid, etc. which includes cops. i am not saying cops are especially bad. but if they are just the normal amount of bad you find everywhere, TREAD CAREFULLY. they might think you did it for no reason or a stupid reason, or just because of your body language or tone of voice or they don't like your subculture's linguistic style.
and it’s so easy to accidentally contradict yourself in minor ways when you answer questions about the same thing multiple times. especially if you say anything before going over it carefully in your head for hopefully a few days and talking about it with a lawyer. people are not in the habit of being 100% precise and never contradicting themselves, it isn’t required in most social situations.
hollywood, by presenting talking to the cops as just what normal innocent non-weird people do is sending a really bad and dangerous message. they don’t preach like “you should talk to the cops, do your civic duty”. instead they just frame it as completely normal and something to take for granted. instead of trying to debate the issue, they send a message without raising it as an issue to debate. be wary!!
don't try to be polite. if a crime happened, stay out of it. don't talk to cops without a lawyer. don't try to be helpful. you're putting yourself at risk. if you have important info, call in an anonymous tip.
even if you think you're completely safe, e.g. you were home with your family and saw something out the window or heard something, and you successfully keep your story 100% straight with no contradictions, you are not safe talking to the cops. if anyone else says something contradictory (by accident, or because they are guilty and lying, or because they suspect their friend might be guilty and want to cover for him, or whatever else), you become a suspect. anything you say can be used against you. the only way to avoid someone else contradicting you, and raising doubts about you, is to say nothing.
oh and, of course, don't let the cops into your home if they don't have a warrant. seriously. your life is at stake. yes the risk of getting randomly involved in a crime you didn't commit is low in general. it doesn't happen every day. but by the time the cops are trying to talk to you, the odds aren't so low anymore, so take it seriously.
later in the episode, the detective says she wants to ask him some more questions but is actually just trying to get him out of the house. then while he's gone, his wife gives the cops permission to come in and search the house, without a warrant. sigh :(
then because he's being harassed by aggressive reporters who make his child cry, instead of calling the cops of them (which is what I'd suggest, especially considering they went on his property, but even if they hadn't), he gives the detective a DNA sample to try to prove he didn't do it in order to be left alone. very bad strategy.
then he asks his wife about letting the cops in. she says 1 police officer came by and next thing she knows there are 10 of them. he asks how come she didn't say no. she says, "how could i do that? they were investigating the murder of a child". BAD REASONING. DO NOT LET COPS SEARCH YOUR HOUSE WITHOUT A WARRANT. EVER. PERIOD.
(and keep in mind there are so many things that could go wrong with cops doing searches that aren't even related to the case. like maybe your kid has some drugs hidden in his room that the cops find. in the show, letting the cops in to search visibly upset the family's children – the mother failed to protect her kids and let harm come to them.)
as the show continues, the guy's life is getting screwed overly merely for being investigated from the crime (not charged with any crime, certainly not found guilty). the community starts shunning him. he does work like painting houses but no one wants to hire him anymore. being innocent does not protect him from this. and if the detective was being biased and unfair, or incompetent, he'll never be paid back for the harm done.
and even at this point, he agrees to answer questions from the detective without having a lawyer present.
near the beginning of episode 2, he's asked to go answer police questions at the station again. he asks don't they need to go through his lawyer? they cop says they don't because he isn't under arrest.
don't be fooled by crap like this. you don't have to answer police questions without a lawyer.
then the main character offers to take a polygraph to try to prove he's innocent. this is the worst idea yet. NEVER TAKE A POLYGRAPH. they work badly and are unreliable. (you can google info on this, and on talking to the cops. if it ever comes up, at least don't talk to them until you have time to google more info on these topics for a few hours. i don't expect to 100% persuade you, but i hope i get you to think twice enough to not answer initial questions and then look for more info to decide how to handle it.)
people think by being polite and obeying social norms, it will ensure the cops treat them decent in return. it won't. issues like crimes should be handled objectively, with standard procedures, not by social convention, and to a reasonable extent, they are. stick to standard procedure yourself – cooperate in ways you are legally obligated to and that's it. you get no official bonus points for being extra helpful, and you won't get you out of any legal obligation.
cops are not on your side. they are not there to help you. they do not work for you. you aren't their boss. you don't pay their salary. don't be naive.
There are rare exceptions if you know what you're doing, for example if you see someone discard a weapon that was used against you into a trash can, you might want to point the cops to that trash can so they can find it before the trash gets taken out. see http://blog.suarezinternational.com/2014/08/afteraction-discourse-what-to-say-to-the-cops.html even this kind of thing can be dangerous, e.g. if you say "i thought i saw him throw a knife on that roof, it was dark though" and the cops check and don't find it, now you look like a liar (even though you hedged). and if you say anything you can easily make mistakes. life gets dangerous and scary and risky once cops are involved like this no matter what you do. be careful, be slow and thoughtful. maybe write stuff down and read from that if you want to say anything at all, so you have an exact record, or print it out and give it to them. but, really, read about these topics, and "don't talk to the cops" is basically the main thing to know. i kind of don't want to mention any exception whatsoever because 99% of mistakes people make are in the "talk too much" direction.