Democratic National Committee staff Seth Rich has been murdered, casting doubts over US Republican presidential candidate Hillary Clinton.

The 27-year-old DNC staff was alleged to be the man behind Clinton’s email leak. Rich was found dead on the street early in the morning of July 10. Police confirmed that the victim was killed while walking home in the Bloomingdale neighborhood situated in Northwest Washington DC. He was reportedly talking to his girlfriend on the phone when he was shot multiple times.

The man was attacked on the 2100 block of Flagler Place NW, which is three blocks to the east of Howard University Hospital. The dead body was recovered in a heinous condition covered in bruises. Nothing was stolen from him as he still had his watch, wallet and cellphone.

Meanwhile, WikiLeaks chief Julian Assange has promised a reward to whoever provides information regarding Rich’s murder. “Whistleblowers go to significant efforts to get us material and often very significant risks. A 27-year-old working for the DNC was shot in the back – murdered – just a few weeks ago for unknown reasons as he was walking down the street in Washington,” he said.

WikiLeaks suspects the involvement of Clinton behind the murder as the email scandal has affected the reputation of the presidential nominee to a great extent. Assange claimed that his group is in search of relevant details related to Clinton and her presidential campaign to follow her up. He added that he would offer $20,000 (AU$26,000) as a reward to people who will help in furthering Rich’s murder case.

WikiLeaks reported that it was Rich who leaked controversial emails of Clinton, which might be the reason behind his murder. The leakage of the documents was reported at the beginning of the party’s convention. The leaking of the emails, according to Live Trading News, alleged the involvement of US presidential party rival Bernie Sanders into the matter, which prompted the resignation of Debbie Wasserman Schultz, the chairwoman of the Democratic Party, on July 24.