Sandra Roberts is the wife of Hank Roberts, who forced her son Nicky to join a fighting club. When the Special Victims Unit started investigating, Hank ordered Sandra to beat him up and say that Stabler beat him up in order to keep him away from him.
Eventually, Hank was murdered but both Sandra's and Nicky's fingerprints were found on the gun used to kill them. Since both Nicky and Sandra confessed to killing Hank and both denied the other one killed him, the case was dropped and Sandra and Nicky were free to go. (SVU: "Pop")