Tanzer has already testified that he and Kissel were each given a milkshake prepared by Nancy Kissel on the afternoon before she allegedly killed her husband.

The effects Tanzer experienced were ``consistent with the drugs found in the stomach contents of the deceased,''expert pharmacologist Professor Yeung Hok-keung of Chinese University said in testimony for the prosecution Wednesday.

Yeung was called to shed light on whether the sedatives and hypnotics found in Kissel's stomach could have come from the now-notorious pink milkshake which allegedly left Robert Kissel unconscious as he was bludgeoned to death.

Yeung said the five different sedatives - Lorivan, Rohypnol, Stilnox, Anatryptaline and Axotal - were usually available through prescription in tablet form and could be crushed into a powdery substance.

``If they were placed in a drink for example, would they dissolve?'' asked lead prosecutor Peter Chapman.

``It depends on the solvent,'' replied Yeung. ``Let's try a milkshake,'' Chapman suggested.

Yeung noted that a milkshake was thick and opaque. ``Most drugs are quite soluble so you can crush the tablets and dissolve them in a drink.''

How about taste? ``I've not tasted the tablets myself,'' Yeung said, ``but I would have thought they had some strange, bitter taste. They are chemicals.''

Yeung was in court last month when Tanzer and his wife testified to the effects he felt after drinking the milkshake at the Kissel apartment.

Yeung noted that, within 10 minutes of drinking the strange tasting, reddish milkshake, Tanzer had arrived back home, red in the face, disoriented, drowsy and, later, with a ``failure to form new memories.''

``This would be in line with the sedative hypnotics of the drugs,'' he said.

Nancy Kissel, 41, is accused of beating her husband to death with a metal ornament November 2, 2003, after serving him a milkshake laced with sedatives. She told a doctor and the police at the time that her drunken husband assaulted her after she refused him sex and that he then disappeared. She denies the murder charge and is out on bail.

The banker's decomposing body was found November 7, wrapped in a blanket in a storeroom at the couple's Parkview residential complex.

During cross-examination, Yeung said he was not aware of the ``timeline'' of Robert Kissel's activities after drinking the pink milkshake.

Alexander King, SC, for Nancy Kissel, informed the professor that her husband was seen playing with their son around 4.40pm that day, 40 minutes after drinking the milkshake.

Images captured on CCTV showed him making a phone call around 5.15pm, an hour after Tanzer had already been seriously affected, King noted.

Given that Tanzer is a big man and was affected by the drugs within 15 minutes, ``if Robert Kissel had consumed the same dosage of whatever it was Mr Tanzer had consumed, you would expect, would you not, for it to have the same pharmacological effect?'' King asked.

Yeung said each individual reacts differently to drugs and it is difficult to make direct comparisons.

``But these drugs do what they intend to do,'' said King, which is to act quickly. ``Yes,'' Yeung replied.

Taking the opportunity to ask Yeung's expert opinion, King read out a statement regarding the use of cocaine. ``New cocaine users often use cocaine to increase productivity in their work, and other activities in their lives, so they can work longer and harder. Dangerous lifestyle choices often follow repeated cocaine use,'' King said.

Yeung said cocaine may cause psychological addiction, paranoia and mood disturbances.

In re-examination, Chapman pointed out that the maximum time before the sedative drugs take effect could be several hours.

He also informed Yeung that Robert Kissel's former Merrill Lynch colleague and friend, David Noh, said he had a phone conversation with Kissel around 5pm that day and found him to be ``generally non-responsive.''

Justice Michael Lunn noted that Yeung had agreed hair samples could be used to test for drugs because some drugs ``bind to hair.''

``What is the position as far as cocaine is concerned? Does that `bind to hair'?'' asked the judge.

``I don't know,'' Yeung replied.

The trial continues today.

albert.wong@singtaonewscorp.com