As questions continue to swirl around the death of Hayden Panettiere, federal authorities are now stepping in.

The U.S. Drug Enforcement Administration is reportedly joining the high-profile investigation after Panettiere, 36, was found unresponsive at Judson Mill Lofts, an apartment complex in Greenville, South Carolina, on Aug. 16, local police previously confirmed to USA TODAY.

The actress and former child star, best known for roles in “Nashville,” “Heroes,” “Ice Princess” and “Bring It On,” allegedly went into cardiac arrest after a possible overdose, according to a 911 call obtained by Reuters, TMZ and other outlets.

Here’s what we know as the investigation moves forward.

Hayden Panettiere ex Brian Hickerson breaks silence on actress’s death

Panettiere’s on-again, off-again boyfriend, Brian Hickerson, released his first statement addressing the actress’s death on Aug. 20 via his attorney, Sloan Ellis, according to TMZ.

“Hayden’s death remains under investigation, and it is important to allow that investigation to proceed,” the statement read. “As has been publicly reported, police confirmed there were no signs of foul play.”

Authorities previously confirmed in a report that Hickerson was on the scene when Panettiere’s body was found, alongside brother Zach Hickerson.

“Out of respect for Hayden’s loved ones and the ongoing investigation, there will be no further comment at this time,” the statement concluded.

DEA inquiry begins in Hayden Panettiere death investigation

As first reported by TMZ on Aug. 19, the U.S. Drug Enforcement Administration is joining the multi-agency investigation into the circumstances of the “Heroes” star’s death. ABC News also reported the development, citing “sources familiar with the matter.”

The DEA declined to comment on the matter when reached by USA TODAY.

The agency, which operates under the U.S. Department of Justice, enforces the country’s controlled substance laws and regulations. The other investigating agencies are the Greenville Police Department and the Greenville County Coroner’s Office.

Hayden Panettiere ‘intervention’: Former director says he was asked to help

Director Griff Furst, who collaborated with Panettiere on the 2025 action horror “A Breed Apart,” reflected on his time working with the actress in an Aug. 19 Instagram video.

Furst said after the film wrapped, he stayed in contact with Panettiere’s team and was later asked to participate in a possible intervention for the actress. However, the director said the meeting did not end up happening, adding, “I wasn’t leading the charge on that, and it wouldn’t have been appropriate for me.”

“A producer or director, no matter how certain you are that an actor or crew member is in a bad situation, you don’t have the proof or the benefit of the time to verify it,” Furst said. “You can adjust the schedule, you can collect internal reporting and you can assign a handler to make sure that that individual is being taken care of as best as they can.”

Hayden Panettiere mother reveals narcotics investigator joined death probe

Panettiere’s mother, Lesley Vogel, is providing an update on the investigation efforts surrounding the actress’s death.

Vogel told NBC News that a narcotics investigator has been brought onto the case, according to Today.com.

“It leads me to believe they have questions,” Vogel told the outlet.

Hayden Panettiere cause of death: Actress was in cardiac arrest

A cause of death for Panettiere has not yet been confirmed.

Medical assistance was administered to Panettiere upon authorities’ arrival, but the actress was later pronounced dead, according to police, who added that no foul play is suspected. The actress allegedly went into cardiac arrest after a possible overdose, according to a 911 call obtained by Reuters, TMZ and other outlets.

Hayden Panettiere toxicology report

An official autopsy or toxicology report on Panettiere’s death has not been released.

The results of these reports could take up to three months to complete, the Greenville County Coroner’s Office previously confirmed to USA TODAY.

allegedly went into cardiac arrest after a possible overdose, according to a 911 call obtained by Reuters, TMZ and other outlets

Hayden Panettiere funeral

A public memorial service has not yet taken place for Panettiere.

Panettiere’s mother, Lesley Vogel, previously confirmed to NBC News that the actress’s body has been returned to the family.

Vogel told the outlet that funeral plans are currently being worked on.

Ruby Rose reveals alleged Hayden Panettiere texts about mother

Following Panettiere’s death, actress Ruby Rose shared several screenshots on social media, showing personal text messages that the actress allegedly wrote before her death.

One of the alleged messages included Panettiere’s reflection on her estranged relationship with her mother.

“I was sobbing over her cruelty yesterday thinking, my god, I’m 36 and she can still cause this kind of pain,” the text read. “I’m her only child left, and this is how she wants to handle the situation?!” (Panettiere’s younger brother, Jansen Panettiere, died in 2023.)

USA TODAY has reached out to Rose for comment.

Hayden Panettiere boyfriend: Who is Brian Hickerson?

Panettiere began dating Brian Hickerson in 2018 following the end of her relationship with former fiancé Wladimir Klitschko.

Over the years, the couple’s on-again, off-again romance became increasingly complicated as he faced multiple arrests and criminal charges stemming from incidents involving the actress. In April 2021, Hickerson pleaded no contest to two felony counts of injuring a spouse or girlfriend and was sentenced to 45 days in jail, four years of probation and 52 domestic violence classes.

Reports following Panettiere’s death indicated the two had allegedly rekindled their romantic relationship privately. They reportedly traveled from Los Angeles to South Carolina the day before Panettiere died, according to E! News. Hickerson and his brother, Zach Hickerson, were at the scene of Panettiere’s death and called 911, according to a police report obtained by USA TODAY.

The report said Panettiere’s ex “did not become emotional” until medics declared the actress dead. He also showed police a “bag of medication” he alleged the actress was taking at the time.

Hayden Panettiere neighbor alleges domestic violence incident involving ex Brian Hickerson

A woman who claims to be a former neighbor of Panettiere is sharing new allegations about the actress’ relationship with Brian Hickerson.

Mia Terrazzas, who allegedly lived next door to Panettiere’s West Hollywood apartment, recalled an incident involving Panettiere and Hickerson in an interview with Inside Edition released Aug. 19. Terrazzas said she called the police at least six times when they were neighbors to report various disturbances near the actress’ residence.

“I saw her leaving on a gurney,” said Terrazzas, although she did not specify when the alleged incident took place. “Brian was right next to her. And I asked her if she was OK, and it looked to me that she had suffered some type of trauma that looked to be battering. It was clear she was terrified.”

Hayden Panettiere Neutrogena comments spark backlash, boycott talk

In her recent memoir, “This Is Me: A Reckoning,” and promotional interviews in May, Panettiere said cosmetics brand Neutrogena, owned by Kenvue, wanted to “fire” her after she shed light on her battle with postpartum depression on “Live with Kelly and Michael” in 2015, less than a year after she gave birth to her daughter, Kaya.

Panettiere told the “Live” hosts she “can very much relate to” her “Nashville” character Juliette Barnes’ depression. She added, “There’s a lot of misunderstanding, and I feel like there’s a lot of people out there who think that it’s not real.”

Panettiere’s comments immediately drew backlash on social media, and criticism of the brand saw renewed fervor after the actress’s death. One Reddit post, which has earned more than 7,200 upvotes, proposed a boycott against Neutrogena.

USA TODAY reached out to Neutrogena for comment.

Gayle King, Holly Robinson Peete criticize Hayden Panettiere mom statements

TV journalist and “CBS Mornings” host Gayle King called out Panettiere’s estranged mother, Lesley Vogel, over remarks she made following her daughter’s death.

In an Aug. 18 phone interview with NBC News, Vogel said Panettiere was “an amazingly talented person in so many departments” but also acknowledged her daughter’s struggles in the spotlight. She added: “Young people who grow up in the entertainment industry – it is a struggle and it’s a very challenging industry, and it’s not unusual for them to sadly find the wrong path.”

King criticized Vogel’s comments, saying, “You know guys, you read this, and all I can think of is ‘Thanks mom for nothing.’

“It makes me so sad that, of the opportunity that you have after your daughter’s death, that that’s what you choose to leave us with,” King added.

Actress Holly Robinson Peete chimed in with similar criticism on social media, writing in an X post, “We know this young lady clearly had so many issues, but if you’re not going to take accountability for the fact that you put her in the business that eventually messed her up, then nothing you say has any integrity.”

If you or someone you know is struggling or in crisis, you can call the Substance Abuse and Mental Health Services Administration Helpline at 1-800-662-HELP (4357).

Contributing: Taijuan Moorman, KiMi Robinson, Sameen Chaudhry and Anthony Robledo, USA TODAY