Authorities have backtracked on initial reports that a Department of Homeland Security whistleblower committed suicide after his body was found with a gunshot wound by a California highway.

Philip Haney, who spoke out against his own agency during the Obama administration, was found dead in Plymouth, about 40 miles east of Sacramento, last Friday.

His body was found in a park and ride area near Highway 16 and Highway 124.

The Amador County Sheriff's Office initially said the 66-year-old was found with what appeared to be a 'self-inflicted gunshot wound'.

They also said a firearm had been found next to Haney and his vehicle.

The sheriff's office have since described those initial reports as 'misinformation' and said they have asked the FBI for assistance in investigating Haney's death.

Philip Haney, who spoke out against his own agency during the Obama administration, was found dead in Plymouth, about 40 miles east of Sacramento, last Friday

'Unfortunately, there was misinformation immediately being put out that we have determined Mr Haney's death to be a suicide. This is not the case,' the sheriff's office said this week.

'We are currently in the beginning phase of our investigation and any final determination as to the cause and manner of Mr Haney's death would be extremely premature and inappropriate.

'No determination will be made until all evidence is examined and analyzed.'

The sheriff's office has scheduled a forensic autopsy to be carried out on Haney's body.

They have also enlisted the help of the FBI to analyze documents, phone records and a laptop that were recovered from the scene and Haney's RV.

'We are currently in possession of his vehicle, the firearm located at the scene and his RV and we will be requesting evidence processing assistance from the FBI on those items as well,' the sheriff's office said.

Authorities said they are also checking for surveillance video from the area.

The area where Haney's body was found is less than three miles away from the RV park where he was living at the time.

Several months before his death, Haney - who formally retired from the DHS in 2015 - told the Washington Examiner that he was considering a sequel to his 2016 book that detailed his experiences within the agency.

He had intended to publish it in mid-spring ahead of this year's election.

Source have also said that Haney had been in contact with officials about possibly making a return to the the DHS.

The sheriff's office has enlisted the help of the FBI to analyze documents, phone records and a laptop that were recovered from the scene and Haney's RV, which was three miles from where he was found

His body was found in a park and ride area near Highway 16 and Highway 124 in Plymouth, about 40 miles east of Sacramento, last Friday

Haney gained national attention in 2016 when he criticized the agency during his testimony before the Senate Judiciary Committeefor its handling of radical Jihadists and Islamic extremists

Haney gained national attention in 2016 when he criticized the agency - which at the time was under the Obama administration - for its handling of radical Jihadists and Islamic extremists.

He testified before the Senate Judiciary Committee that the DHS ordered him in 2009 to delete hundreds of files that showed links between people and Islamic terror groups.

Several months before his death, Haney - who formally retired from the DHS in 2015 - told the Washington Examiner that he was considering a sequel to his 2016 book (above) that detailed his experiences within the agency

The whistleblower testified that several terror attacks in the U.S. could have been thwarted if some of those files had not been deleted.

In an opinion piece for the Hill prior to his testimony, Haney wrote: 'It is very plausible that one or more of the subsequent terror attacks on the homeland could have been prevented if more subject matter experts in the Department of Homeland Security had been allowed to do our jobs back in late 2009.

'It is demoralizing - and infuriating - that today, those elusive dots are even harder to find, and harder to connect, than they were during the winter of 2009.'

At the time of Haney's testimony, Republicans questioned former Obama-era DHS Secretary Jet Johnson about the allegations.

Senator Ted Cruz asked: 'Was Mr Haney's testimony that the Department of Homeland Security order over 800 documents... altered or deleted accurate?'

Johnson replied he had 'no idea' and denied knowing who Haney was.

'I don't know who Mr Haney is. I wouldn't know him if he walked into the room,' he said.