The body was identified as Roosevelt Rene, 25, a Jenkins family friend who had been living at the house, according to the Bergen County Prosecutor's Office.
Police sources told ESPN's Dianna Russini that they are looking to question Janoris Jenkins' brother William Jenkins who has fled the state of New Jersey. Police are asking William Jenkins to come back voluntarily for questioning. It's believed he is in Florida.
Pending the results of a post-mortem exam by the Bergen County Medical Examiner's Office, police are treating the case as a homicide investigation and believe that the cause of death is "highly suspicious," separate police sources told Russini and ESPN's Josina Anderson.
Bergen County Prosecutor Dennis Calo had earlier confirmed that an investigation was taking place at the address.
Janoris Jenkins was not at home when the body was discovered and has been in Florida since the completion of Giants minicamp two weeks ago, sources said. He is aware of the investigation, and multiple sources who have communicated with the cornerback told ESPN that he is "good" and "just waiting for the legal process to play out."
Jenkins has been advised by attorneys to remain in Florida, sources said.
The Giants said that they "are aware of and monitoring the situation."