In general, I think graduate students want students to pursue their entire PhD candidacy at a given institution. Moreover, schools may be reluctant to count work done a long time ago as part of the requirements for obtaining a degree, as it likely sets a bad precedent.

Moreover, there's the question of financing. If you're in a program where students are financed through TA's, it's a lot easier to convince a school to take a chance, rather than in the sciences. The reason for this is that funding in the sciences is often tied to specific projects—which means that you will most likely need to change topics if you pursue a PhD in such a department. This would of course set your time to degree back considerably.

That said, you may find a sympathetic department that's willing to take a chance. My best advice is try to talk to the graduate admissions officers of some of the departments you're thinking of applying to. They'll help you to figure out what are the requirements and possibilities.

In general, I think graduate schools want students to pursue their entire PhD candidacy at a given institution. Moreover, schools may be reluctant to count work done a long time ago as part of the requirements for obtaining a degree, as it likely sets a bad precedent.

Moreover, there's the question of financing. If you're in a program where students are financed through TA's, it's a lot easier to convince a school to take a chance, rather than in the sciences. The reason for this is that funding in the sciences is often tied to specific projects—which means that you will most likely need to change topics if you pursue a PhD in such a department. This would of course set your time to degree back considerably.

That said, you may find a sympathetic department that's willing to take a chance. My best advice is try to talk to the graduate admissions officers of some of the departments you're thinking of applying to. They'll help you to figure out what are the requirements and possibilities.