Emergency services were called to the property, with reports stating that she was already in cardiac arrest when first responders arrived.

Her on-and-off boyfriend, Brian Hickerson, was at the property and reportedly attempted to help her before paramedics arrived.

According to previous reports, Hickerson administered Narcan and CPR was performed in an attempt to revive her.

The Greenville County Coroner’s Office subsequently confirmed that an autopsy had been completed.

At the time, officials said there were no signs of trauma that could have contributed to Panettiere’s death.

Her cause and manner of death, however, were left pending further investigation and additional testing.

Toxicology results were still pending

In the weeks following Panettiere’s death, attention turned towards toxicology testing.

Authorities had warned that the results could take several weeks to complete, meaning an official cause of death could not immediately be established.

The investigation also expanded beyond South Carolina.

According to People, the Drug Enforcement Administration became involved, with investigators looking into possible sources of medication and speaking to people connected to Panettiere.

Hickerson also reportedly met with DEA officials as part of the investigation.

Importantly, Hickerson has not been named as a suspect in Panettiere’s death.

Brian Hickerson had been with Panettiere

Hickerson’s involvement in the investigation has attracted attention because he was reportedly at the South Carolina property when Panettiere was found unresponsive.

He had also been travelling with her shortly before her death.

According to reports, police were shown a bag containing medication that had belonged to Panettiere.

Some of the medications reportedly listed in police records were redacted, while reports have indicated that several different medications were involved.

Investigators have been attempting to establish exactly what Panettiere had taken and where any medication had come from.

The situation surrounding Hickerson has also remained complicated because of his previous relationship with the actress.

The pair first began dating in 2018 and had an on-and-off relationship over several years.

Hickerson had previously faced legal consequences relating to domestic violence involving Panettiere, later pleading no contest to felony charges in 2021.

Despite the history between them, authorities have not publicly accused him of causing Panettiere’s death.

Hayden had previously spoken openly about addiction

Panettiere had been remarkably candid about her struggles with addiction throughout her life.

The actress rose to fame as a teenager, becoming particularly well known for playing Claire Bennet on Heroes before starring as Juliette Barnes on Nashville

She later spoke publicly about her struggles with alcohol and opioid addiction.

Panettiere revealed that she had first been introduced to so-called ‘happy pills’ when she was just 15 years old.

She said the pills had been given to her before red-carpet appearances because she was expected to appear energetic during interviews.

In later years, she described how her relationship with substances had become increasingly difficult.

Her struggles were also discussed in her memoir, This Is Me: A Reckoning, which was released just months before her death.

Panettiere had previously discussed the physical and emotional difficulties she experienced during her adult life.

Following the birth of her daughter, Kaya, in 2014, she spoke about experiencing postpartum depression and subsequently struggling with alcohol.

She also revealed that her drinking had caused serious health problems.

At one point, Panettiere said she had developed jaundice and had been warned by doctors about the condition of her liver.

Her mother, Lesley Vogel, also previously described Panettiere as having been in considerable physical pain in the period before her death.

Vogel said her daughter had experienced symptoms including pins and needles in her lower extremities and had struggled to physically function.

Panettiere had reportedly seen several doctors and explored different treatments while attempting to understand what was causing her symptoms.

Investigation reportedly takes a new turn

While the toxicology results remain crucial, investigators have reportedly been following another important lead.

According to TMZ, authorities are now investigating a Los Angeles-based individual described as Panettiere’s long-time drug dealer.

The report claims Panettiere had obtained several black-market prescription medications before travelling from Los Angeles to South Carolina.

The DEA is reportedly attempting to establish the relationship between Panettiere and the alleged supplier and determine where the medication came from.

The investigation is taking place across both Los Angeles and South Carolina.

Authorities are reportedly attempting to trace the medication involved back to its source.

But until the toxicology results are officially released, the precise circumstances of Panettiere’s death remain unconfirmed.

The latest developments come amid further attention surrounding Brian Hickerson and his brother Zach.

The pair were involved in an incident at a South Carolina restaurant on September 12, with Zach later arrested for disorderly conduct while Brian was detained and subsequently released.

According to TMZ, an eyewitness claimed the brothers had been approached and allegedly heckled about Panettiere’s death before the situation escalated.

Following his release, Zach spoke about what he described as misinformation surrounding the actress’ death, saying he was frustrated that rumours were being shared online and that people were then making assumptions based on them.

He suggested he would eventually share his side of the story, while Brian was also heard telling police that information about Panettiere’s death had been leaked.

New report claims one pill may have been fatal

Now, a major new detail has emerged.

Multiple law-enforcement sources reportedly told TMZ and the New York Post that Panettiere may have taken just one pill on the morning of her death, which investigators believe could have been oxycodone.

The sources reportedly believe that pill may have been contaminated with fentanyl.

According to TMZ, authorities’ current working theory is that the suspected fentanyl-laced oxycodone may have caused Panettiere’s fatal overdose.

The New York Post has also reported the development, saying authorities believe Panettiere took a single pill that was thought to be oxycodone but may have contained fentanyl.

However, this has not yet been officially confirmed as Panettiere’s cause of death.

Toxicology results are still pending, and investigators are reportedly working to establish whether the medication was contaminated and, if so, where it came from.

The development could therefore prove significant in determining not only what happened to Panettiere, but also whether anyone else could ultimately face consequences in connection with the medication.