There were six different types of prescription drugs in the room, including pills to treat insomnia and anxiety, and an antihistamine, according to two law enforcement officials who spoke on condition of anonymity because the investigation is ongoing.
A rolled-up $20 bill was found on the floor near the bed, but New York Police Department spokesman Paul Browne said lab tests found nothing to indicate the bill had been used to snort drugs. Police also said no illegal drugs were found in the apartment.
Authorities believe it will take about 10 days and additional tests to determine Ledger's cause of death.
Ledger's body was discovered Tuesday afternoon by Wolozin, who arrived at the apartment for an appointment with him, police said. Wolozin was let in by Ledger's housekeeper, Teresa Solomon.
Solomon said she went into Ledger's bedroom and heard him snoring Tuesday afternoon at 1 p.m. Wolozin arrived around 2:45 p.m., called Ledger's cellphone and knocked on his bedroom door, but got no answer. When she opened the door, she found him naked, face-down and unresponsive.
Wolozin proceeded to use Ledger's phone to repeatedly call Olsen. Olsen said she would send members of her private security team to the residence, according to reports released by police. Wolozin then called 911.
Paramedics arrived at 3:33 p.m., according to the timeline released by police. Three minutes later, Ledger was pronounced dead. Authorities told The New York Post they believe Ledger had already been dead for hours.
News of Ledger's death hit Hollywood fast.
News of Ledger's death came just as model Helena Christensen was on her way to visit him, she told Women's Wear Daily. Christensen, who was rumored have hooked up with Ledger this past fall following his split from Williams, told the fashion publication: "My heart goes out to his family. I am just beyond sad at this point, and shocked.
"I was on my way over to pay him a visit when I found out. I had just left him a message and heard his voice on the machine," she continued. "He was such a special and genuine person, so extraordinarily talented because he was so raw and honest with his feelings. He was so full of life, so electric. ? This is immensely sad."
Lee Daniels, who produced the critically acclaimed "Monster's Ball" in which Ledger starred, strongly disputed any notion that Ledger had a drug problem.
"The definition of substance abuse is really up to one's perspective," Daniels said. "I didn't see him as a drug addict. I saw him as someone who enjoyed life. I know drug addicts; he was not a drug addict."
He said that he saw Ledger a couple months ago and that he was in great spirits. "He was in a good mood, he was in a great place. ? He was excited about living in New York."
Two hours after his death was first reported, Nicole Kidman, who hails from Ledger's home country of Australia, released a statement to reporters saying, "What a tragedy. My heart goes out to his family."
The superintendent of the Ledger's apartment building, Tamba Mossa, told ABCNEWS.com that Ledger had "been renting the apartment for about four months" but he didn't know who owned the loft. Mossa added that he was surprised to learn about Ledger's death, saying the actor had always been "very nice" and would often go on walks with his young daughter.