( CNN ) -- No cyanide remained in the exhumed body of Illinois lottery winner Urooj Khan , preventing investigators from determining how the toxin entered his body , the Cook County medical examiner said Friday . Still , Dr. Stephen Cina maintained his determination from January : that blood samples taken after Khan 's death in July show the 46-year-old died of cyanide poisoning and that the manner of death was homicide . Officials in January exhumed the body of Khan -- who died the day after the Illinois lottery issued him a check for about $ 425,000 for winning a scratch-off game -- hoping to determine how cyanide entered his system . `` Cyanide has a short half-life , and it may be lost over the postmortem interval unless the tissues are adequately preserved , '' Cina said Friday . `` In this case , due to advanced putrefaction of the tissue , no cyanide was detected '' after the exhumation . Investigators initially ruled Khan 's manner of death natural . But after being prompted by a relative , technicians retested Khan 's blood , leading to Cina 's cause of death determination in January , more than a week before the body was exhumed . Cina also said Friday that coronary artery disease was a contributing cause to Khan 's death , because the autopsy showed one of his major coronary arteries was 75 % blocked . `` Since cyanide affects oxygen utilization in the tissues , it follows logically that a natural disease process that already limits blood flow to the heart could render an individual particularly susceptible to death due to this toxin , '' he said . Before the exhumation , Cina said that cyanide can evaporate from a body after death and that it was possible it would not still be present . The autopsy results have been turned over to Chicago police , who have been investigating the case as a murder . CNN 's Shawn Nottingham contributed to this report .
Coroner : No cyanide found in post-exhumation autopsy , likely because death was too long ago . But the coroner says cyanide poisoning still is the cause of death . Comment: Toxicology tests found cyanide in his blood after a tip from a relative .