Rhetorical situation.
You've been implicated in a criminal case, effectively unwitting accomplice to say... A murder. Several murders. You are facing 25+ to Life in jail, unless you give up the name(s) of the people whom actually did the crime. If you give up the names, the court will be lenient, likely allowing probation after a year or so.
However, the people who did the crime are dangerous people. People you have no reason to believe the system can protect you from. Brotherhood, Yakuza, D-Company, 14K, Cosa Nostra, whatever. You're fairly certain (based off other people, likely dead) that even under witness protection, and other services provided by the government, you'll be a dead person within a year of getting out a jail. Possibly even before that.
Worse, they may be vindictive enough to make you suffer first, and target your family and friends. They are not on a time restraint. You are. Not only that, but if you don't give up the names, there may be more deaths. You don't know, as their business is not your business.
Given the nature of organized crime, and their ties to particular nations, please keep the discussion clean, and avoid any ethnic flaming. This is about your decisions, not the groups.
So what'll it be? 25-Life, or being hunted down like a dog?
EDIT: These people are not your friends, allies, or comrades. You are being blamed, essentially. You owe them nothing, nor they you. You got caught up in something that got out of control quickly. Example: What was supposed to be a silly internet credit card fraud scheme for 10K ended up in multiple murder/homicide.
EDIT2: Moving elsewhere or attempting to get a new identity will likely not help. You know them well enough to know that others have done the same, and ended up six feet under.
EDIT3: Whatever group you have gotten mixed up with, they know things. They know if you've kept quiet or not, and if you don't give up the names, you can safely assume that you and anyone else involved with you are safe. This is purely a "Jail or Death" scenario.