Like a good guy version of Lois Reiss...

However, because this has been done in real life, there is a lot out there that you can use to research how she did it, how she got caught, where she slipped up, etc. In fact, if your character knows about this, can try to use this to avoid those errors.

However, the protagonist taking on the role of a police officer elsewhere in the country, maybe taking advantage of no cross-jurisdiction communication or the like, is a nice twist, and with her background, is one she should be able to maintain.

And when the husband comes back (assuming you are still going that route)... new life, meet old life...