Maria Cabrera Gonzalez is no cop. But her girlfriend is. Prosecutors say Cabrera — without authorization and posing as a plainclothes detective — was riding along with that girlfriend, Miami Police Officer Sheila Belfort, when the two pulled over a motorist in June 2014. But the misconduct didn’t stop there. After the motorist, an undocumented immigrant, was jailed, Cabrera shook down his family for $2,400, promising that the cash would free him from jail and help with “immigration concerns.” The motorist later complained to Miami police’s internal affairs unit. On Friday, Cabrera, 50, pleaded guilty to impersonating a police officer...