Woolmer was found dead on March 18, a day after Pakistan were eliminated from the World Cup following a shock defeat by Ireland.
He was found unconscious in his hotel room and pronounced dead at hospital. Police said he was strangled in a crime still shrouded in mystery.
The BBC's Panorama programme, in an investigation due to be screened on Monday night, says that preliminary toxicology tests showed that Woolmer, who was 6ft 2in (1.88 metres) tall and heavily built, was subdued by a drug that left him helpless to fight back against his assailants.
He was then both strangled and smothered, the BBC World Service said in a report ahead of Monday night's broadcast.
The drug used had not yet been identified, it said.
Newspaper reports said the programme would also screen the last recorded image of Woolmer, taken after Pakistan's shock defeat.
A blurred recording from a CCTV camera at the Pegasus Hotel shows the coach heading back to his room on the 12th floor, where his body was found the following morning.
Police in Jamaica have not yet made any arrests in connection with Woolmer's death, which cast a huge shadow over the cricket World Cup that ended on Saturday and was won by Australia.
Speculation about his murder has included suggestions that he had uncovered a match-fixing scandal, or that he was killed by a supporter with a grudge. The 58-year-old former England player's body arrived back in Cape Town, where he lived, on Sunday.
The BBC said in its radio report that the findings suggested his killing was premeditated rather than being "a spur-of-the-moment act of violence".
