Anytime you talk to the police, there is a chance you will admit guilt without any benefit in return. Police commonly give a vague promise to put in a good word with the prosecutor for people who cooperate. The police may indeed tell the prosecutor that you cooperated with them, but that just will not get you a deal any better than what a lawyer could get for you. Allow your lawyer to extract concrete, definitive deals from the prosecutor instead of vague promises.
Also, with how many laws are on the books these days, you may unintentionally admit guilt to crimes that the police had not been previously investigating. Even if you are innocent of the original charge, that gives the government leverage against you, which they can use to conduct further investigation. Information you divulge gives the police tools to request search warrants, wiretaps, or other investigative tools to further incriminate you. Instead of ending the investigation, it will be prolonged.
If you feel you must admit guilt—you need to get something off your conscience—you’re better off telling a member of the clergy or your therapist. Confession may indeed be good for you, but that’s a matter between you and your conscience or your God. Talking to the police will do little to assuage your conscience.
Some people feel that there is no harm to admitting guilt if it only tells police what they suspect or know already, That simply isn’t true. For any number of reasons, witnesses and police officers are frequently unavailable to testify. If a key witness is unavailable, your lawyer may be able to negotiate a better deal, or perhaps the government will be forced to drop the case altogether. However, if you have already admitted guilt, it doesn’t really matter if key witnesses can’t testify. A confession is sufficient by itself to get a conviction.
There’s simply no rush to admit guilt. You can always take a plea offer from the government later, but you cannot take back your impetuous decision to tell the police everything. Most criminal proceedings end in a guilty plea anyway. If you allow your lawyer to do their job, you can extract some sort of promise from the government in exchange for your confession. Regardless of the reason you want to talk to the police, you’ll be better served if you wait until time has passed and you have had a chance to talk to a lawyer.