I do not see a jurisdictional; problem here. Furthermore, if you will pardon me for pointing this out, you were not forced into a plea bargain. You were simply put face to face with a very ugly reality and had a nasty and very unpleasant choice to make. You made it. The alternative was trial with a risk of conviction. It is unfortunate, but it does not help to distort what happened.
If the crime was committed in california, that would be enough for jurisdiction. if you were extradited, it meant that you waived it and allowed yourself to be sent to california. you also signed the plea agreement knowing you could have challenged the state's charges, so unless someone physically threatened you or a loved one, you were not threatened under the eyes of the law. If you want to contest your guilty plea, california probably has a time limit within which to contest it. you need to hire a california attorney or apply for a california public defender attorney on the issue.
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