Asked about the timeline of the examination, Bolcer said Tuesday, "It varies on a case by case basis, but in general, it's a matter of a few weeks. It's not a matter of days."
Bolcer stressed that additional investigation to determine the cause of death is common practice and urged against reading too much into it.
"It is routine, and it would be ill-advised to draw any definitive conclusions from this," the spokesperson said.
Generally, the procedures include histology, toxicology and tissue testing, Bolcer added.
Churkin, 64, who had served as Russia's Permanent Representative to UN since April, 2006, died in New York City on Monday, one day before his 65the birthday.
US media reported that the Russian diplomat had died after suffering a heart attack at Russia’s UN mission in Manhattan. He was rushed to a hospital where he was pronounced dead.
On Tuesday, however, the medical examiner's office said that further investigation into the cause of death is required before any definitive conclusions can be made.