A former guard supervisor at the notorious Rikers Island jail is now heading to prison, this time as an inmate. A judge sentenced Terrence Pendergrass to five years in federal prison after a jury found him guilty of refusing to help a 25-year-old Rikers inmate—who was mentally ill—after he swallowed detergent. According to a witness, even after officials reported that the inmate appeared to be dying, Pendergrass not only refused to call for help, he made another officer hang up a phone he was planning on using to alert medics. The prisoner was found dead the following morning …