CHICAGO (AP) — The body of a Chicago man who was poisoned with cyanide after winning the lottery was exhumed Friday for an autopsy that authorities hope will help solve the mystery surrounding his death.

A black hearse escorted by four police cars carried away the body of Urooj Khan from a cemetery on the city's North Side around 9 a.m., and the Cook County Medical Examiner's Office was expected to perform the autopsy immediately, spokeswoman Mary Paleologos said.

She said examiners will take blood, tissue, bone, hair and nail samples. They'll also examine the lungs, liver, spleen and contents of the stomach and intestines. Paleologos said tests on Khan's organs also may determine whether the poison was swallowed, inhaled or injected.

The autopsy was expected to be finished by Friday afternoon, though it will take two to three weeks to get test results, she said.

Khan, 46, died in July as he was about to collect $425,000 in lottery winnings. His death initially was ruled a result of natural causes. But a relative asked for further tests that revealed in November that he had been poisoned.

Khan's wife, Shabana Ansari, and other relatives have denied any role in his death and expressed a desire to learn the truth.

Authorities remain tightlipped about whom they may suspect.

At dawn on Friday, a backhoe at Rosehill Cemetery began scooping up dark clumps of ground hardened by the cold weather. Two men then finished the work with shovels, and a Muslim cleric said prayers beside Khan's grave. His body was placed in a white bag and loaded into a hearse.

One of Khan's brothers was present, along with officials from the medical examiner's office and Chicago police detectives.

Police kept about half a dozen TV news crews at a distance, beyond the cemetery's fence, and two news helicopters circled overhead.

Khan had come to the U.S. from his home in Hyderabad, India, in 1989, setting up several dry-cleaning businesses and buying into some real-estate investments.

Despite having foresworn gambling after making the haj pilgrimage to Mecca in 2010, Khan bought a lottery ticket in June. He jumped "two feet in the air" and shouted, "I hit a million," he recalled at a lottery ceremony later that month.

He said winning the lottery meant everything to him and that he planned to use his winnings to pay off mortgages, expand his business and donate to St. Jude's Children's Research Hospital.

He was just days from receiving his winnings when he died before dawn on July 20.

The night before, Khan ate dinner with his wife, daughter and father-in-law in their house in Chicago's North Side neighborhood of West Rogers Park, home to many immigrants from India and Pakistan.

Sometime that night, Khan awoke feeling ill and collapsed as he tried to get up from a chair, his wife has said, according to the Chicago Sun-Times.

With no outward sign of trauma and no initial suspicions, authorities performed only a basic toxicology screening and an external exam of Khan's body in July. They determined that he died of natural causes, as a result of a narrowing and hardening of coronary arteries.

But a concerned relative — whose identity remains a mystery — came forward days later with suspicions and asked authorities to look deeper. They then carried out a full toxicology screening on fluids that had been drawn from the body and found a lethal amount of cyanide in his blood, leading the medical examiner in November to reclassify the death a homicide.

Exhuming the body will allow authorities to conduct an autopsy and, depending on the condition of the remains, to gather more data that could be presented in court if the case goes to trial. It could also provide important clues about how the cyanide entered his body.

Medical Examiner Stephen Cina was to hold a press conference Friday afternoon to give details on the condition of the body and how much testing they were able to do.

Khan was given a religious burial and his body was not embalmed.

His body is to be reburied Monday.

Khan died without a will, opening the door to a court battle. The businessman's widow and siblings fought for months over his estate, including the lottery check.