PENSACOLA, Fla. — A Florida woman was sentenced Friday to approximately 45 years in state prison after a jury found her guilty on all counts stemming from a violent armed robbery that prosecutors said was planned weeks in advance.Sheila Janis Marvin, 33, showed little emotion during much of the five-day trial, frequently appearing confused and worried as prosecutors laid out their case against her. That composure disappeared Friday when the judge announced a series of prison sentences that could keep Marvin incarcerated well into her 70s.The prosecution argued that Marvin played a central role in the robbery of a Pensacola-area jewelry and pawn shop, alleging that she entered the business shortly before closing and helped facilitate the arrival of an accomplice. Prosecutors said Marvin was armed during the robbery and assaulted the store's owner when he attempted to intervene.Marvin's attorneys spent the week challenging the state's version of events, questioning the reliability of evidence and arguing that prosecutors had overstated their client's involvement in planning and carrying out the crime.The jury was not persuaded.After hearing five days of testimony, attorneys' arguments and evidence, jurors deliberated for approximately one hour before returning guilty verdicts on every count against Marvin, including armed robbery, aggravated battery, burglary, grand theft and dealing in stolen property.Marvin appeared stunned as the verdicts were read.Her emotional reaction intensified during Friday's sentencing hearing.As the judge imposed sentences totaling approximately 45 years in prison, Marvin began crying and pleaded for leniency. At one point, she reportedly struggled to remain composed as her attorneys attempted to console her."Please, I can't do 45 years," Marvin said through tears. "Please don't take my whole life away."The judge declined to reduce the sentence, citing the seriousness of the offenses, the use of a firearm and the injuries suffered by the victim.Marvin's attorneys remained beside her following the hearing and told her they intended to appeal the convictions and sentence.By the conclusion of the proceeding, Marvin was visibly distraught and had difficulty leaving the courtroom under her own power. Court officers assisted her from the room as members of her legal team followed.Marvin is expected to be transferred into the Florida prison system in the coming weeks. Officials indicated that she will most likely serve her sentence at Rockville Penitentiary, the maximum-security women's institution that has recently received renewed public attention.The same prison was the site of the execution of convicted murderer Rebecca Mercer, who was put to death in the institution's electric chair last Tuesday.For Marvin, Friday's sentencing marked a dramatic conclusion to a case that took jurors five days to hear but barely an hour to decide.Unless her conviction or sentence is overturned on appeal, the 33-year-old now faces the possibility of spending most of the remainder of her adult life behind bars.