Legal Question in Criminal Law in California

If you make an agreement with the police that they will drop the charges and release you in return for your helping them arrest someone else, and you fail to keep up your part of the agreement, why would you think that they have to keep up their part of the agreement? You broke the terms of the agreement so everyone goes back to the initial position, with you being under arrest. The agreement is perfectly valid and not against public policy.

As to the claim that the officer threatened to plant evidence in your house, do you really beleive anyone will think that is true. You are already arrested for a felony, probably enough of a charge for Child Support to remove your children [if you are convicted of a felony, how will you take care of the children]. So why does the police officer need to make such a threat?

This is a good example of why you should never make deals with the police, or speak to them at all. Your attorney should be doing the bargaining with the prosecuting attorney. I don't know which is more of an outrage, the fact that in California people's children can be taken on a whim, or that some police officers' moral compasses are sufficiently askew that they would hurt innocent children, stealing them from their parents and sentencing them to foster care or a forced adoption, out of spite. I would write to the police agency that employs this officer and report that he threatened to take your kids in retaliation for your not cooperating. They might, of course, retaliate against you for filing a complaint, but you need to do it anyway.

I'd call Internal Affairs.

You can still be arrested, so you should only have an attorney contact the police.

Be careful