Fresh details have emerged in the investigation into Hayden Panettiere’s untimely death.

Panettiere, 36, was found dead of a suspected overdose on August 16 at an Airbnb in Greenville, South Carolina, where she had traveled with on-off boyfriend Brian Hickerson, a native of the state. 

More than six federal agents raided the actress' West Hollywood home on Tuesday, a source told US Weekly.

The witness said they were inside Panettiere's building when the agents entered, adding that they obtained a warrant to search the premises.

Panettiere's boyfriend and his brother, Zach, were both at the scene when the 36-year-old was pronounced dead.

Brian administered Narcan to the Heroes actress, Zach has now revealed in a statement to TMZ.

Zach, who said he wanted to 'clarify my involvement' in the situation, said he was calling 911 while Brian gave Panettiere the medication, which is typically administered to reverse an opioid overdose.

The trio were planning to get lunch and go indoor golfing after Zach attended church.

He called and texted Panettiere and his brother as he was leaving the Sunday service, but didn't hear back from them, he recalled.

Zach assumed the pair were sleeping so he drove back to the rental, but he didn't have the door code to the unit so he couldn't get in.

'I knocked loudly which apparently woke Brian up from a nap they were both taking on the pull out couch bed in the living room. When we went in and tried to wake Hayden up for lunch, we realized she was unconscious,' he said.

'I immediately called 911 and Brian gave her Narcan. We then jointly performed CPR while 911 was on speaker until Fire and EMS arrived.'

'At that point we watched as they tried every measure possible to save her life,' he added.

The Drug Enforcement Administration (DEA) has joined the probe into the actress's death.

Greenville County Sheriff's Office said that the post-mortem had been completed and that no signs of trauma were found on the star's body.

Further investigations will now take place to establish her cause of death, with chief deputy coroner Shelton England telling the Daily Mail that it was too early to discuss the drug overdose theory.

A Greenville police officer who responded to the residence was met by the brothers and then observed paramedics performing CPR on an unresponsive woman, according to a police report. 

'The patient did not seem to have any obvious physical reasons to be unresponsive,' the officer noted. After attempting lifesaving measures, the emergency workers declared Panettiere dead at 2.31pm on Sunday.

Narcan was found on a mattress inside the South Carolina property.

Brian addressed the star's death through his lawyers: 'Hayden's death remains under investigation and it is important to allow that investigation to proceed,' said his attorney Sloan Ellis, from the Ellis Hinton law firm.

'As has been publicly reported, police confirmed there were no signs of foul play.

'Out of respect for Hayden's loved ones and the ongoing investigation, there will be no further comment at this time.'

In the aftermath of the tragic death, there has been rampant speculation on the internet by some who knew the actress and others who did not at all.

Panettiere's rep released a statement to Us Weekly which read: 'Many people who were not close to Hayden are using her death as an opportunity to fuel gossip and speculation about a situation they knew very little about.

'It is deeply disrespectful to her memory and to those who knew and loved her and are actively grieving this tremendous loss.' 

The representative did invite anyone with actual helpful information which would aid the ongoing investigation to come forward.

They continued: 'If you have legitimate information that could be helpful, please contact law enforcement rather than turning to social media to speculate publicly about something you do not fully understand.'

The statement concluded by saying that there are critical details regarding the star's death that have not surfaced and that the late actress' inner circle is doing what they can to aid in the investigation.

Panettiere's rep concluded: 'There is much more to this story than what is currently being discussed publicly, and those closest to Hayden are actively cooperating with the ongoing investigation to help ensure that the truth comes to light and that justice is properly served.'

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