The 52-year-old surrendered to begin serving a five-year-sentence for weapons possession.
Sheehan, who claimed to have suffered years of abuse, says she feared for her life when she fatally shot her husband, retired NYPD Sergeant Raymond Sheehan, in the family's Howard Beach home in February, 2008.
Three years later, a jury acquitted the mother of two of murder, but found her guilty of weapons possession. The fact that she used two guns to shoot her husband 11 times and continued to pump bullets into his body when he was no longer an apparent threat was a problem for the jury.
Her attorneys are appealing based on her argument of self-defense.
"The issue here is Barbara only used the gun in self-defense. There was no period of time when she used the second gun for anything but self-defense That is the issue that we had raised with the court of appeals," Niall MacGiollabhui said..
Sheehan's family shouted words of encouragement as she was led away in handcuffs.
No one answered the door at the family home, but her neighbors offered their support. Tony Clemente has lived next door for 23 years.
'It shouldn't have gone this far," he said, adding that he does not think she should be going to prison.