I work with a number of retired top brass from the NYPD. Each of them went to grad schools, including law school and public policy programs at Columbia and Harvard, paid for by the NYPD. Also, the time they took away to attend school full time counted towards their 20 years, and they were still paid their normal salary--and rose through the ranks.
In retirement, they've each moved on to even more lucrative careers, in addition to that great pension, that's considering after 5 years in the NYPD base salary is somthing like $90K.

I think you'll find the majority of Police don't take advantage of those opportunities available, but the smart ones do--including the female police.