The FBI is investigating whether a Pakistani grocer in Dallas was shot dead to avenge last week's terrorist attacks.
Police have been unable to determine a motive for the murder of muslim Mr Waqar Hasan at his shop four day's after the attack on New York.
Police say there was no evidence of robbery or a struggle.
Family members fear the shooting was a response to attacks in New York and Washington.
Homicide Sergeant Mr Larry Lewis told The Dallas Morning News the FBI have been called in because of the possibility the killing was a hate crime.
"We have, just in case of recent events, notified the FBI," he said. "I have nothing to prove it was a hate crime, but nothing to disprove it."
Mr Hasan's cousin, Mr Khalid Ishaq, said: "I really think it's someone trying to take revenge."
His brother-in-law Mr Nadeem Akhtar, said he was asked about Tuesday's attacks during interviews with homicide detectives and FBI agents.
But family members say the shooting of Mr Hasan, who was not actively political or religious, has left them fearful.
Mosques in Dallas have also been targeted for apparent revenge attacks. Last week shots were fired into two Dallas mosques and a firebomb was thrown into one in nearby Denton.