KUALA LUMPUR, Malaysia — Determining whether poison killed the half brother of North Korea’s leader in a busy airport is proving difficult for Malaysian officials, who said Tuesday that autopsy results are so far inconclusive.

More than a week has passed since Kim Jong Nam was approached by two women at a budget air terminal in Kuala Lumpur and apparently attacked in the face with an unknown substance. Kim did not suffer a heart attack and had no puncture wounds, such as those a needle would have left, Director General of Health Noor Hisham Abdullah told reporters. He did not dismiss poison as a potential cause.