CHICAGO (CBS) — The cause of Charlie Trotter’s death remained undetermined following an autopsy by the Cook County Medical Examiner.

Preliminary findings on Wednesday indicated found no sign of foul play.

Trotter was found unresponsive in his Lincoln Park home on Tuesday.

“At the discretion of the Medical Examiner, additional tests, including a toxicology analysis, will be conducted before a final cause and manner of death is issued,” spokesman Frank Shuftan said in a statement.

The tests are expected to take six to eight weeks to complete.

Trotter appeared at a culinary conference on Sunday in Jackson Hole, Wyo. Attendees at the event noticed that Trotter seemed to be acting strange on stage.

Mary Grossman, publisher of the Planet Jackson Hole newspaper, was at the event and said Trotter “didn’t look well.”

“He seemed tired and was sweating and his hands were shaking,” she said.

At one point, Trotter stopped his speech, which Grossman described as rambling, and began to repeat himself.

A source told WBBM Newsradio’s Steve Miller that Trotter had hypertension and did not always take his medication and also missed a recent doctor’s appointment.

The demanding and mercurial Trotter closed his namesake restaurant in August 2012 after 25 years, during which he won a multitude of top culinary awards.

Published reports on Wednesday indicated the iconic chef had been warned not to fly due to a health condition.

A memorial service for Charlie Trotter has been scheduled for 10 a.m. Monday at Fourth Presbyterian Church, according to his mother, Dona-Lee Trotter. The service will be open to the public, and chefs and other friends from Chicago and around the country are expected to attend.