Brisbane estate agent Gerard Baden-Clay has been committed to stand trial in the Supreme Court over the murder of his wife Allison.

Baden-Clay is accused of murdering his wife and interfering with her corpse in Brisbane's west last April.

The body of the 43-year-old mother-of-three was found under a bridge at Kholo Creek in Brisbane's western suburbs 10 days after she went missing from the family's Brookfield home.

At the end of a six-day committal hearing today, Baden-Clay told Chief Magistrate Brendan Butler he would plead not guilty.

The date of the trial is yet to be fixed.

This morning a forensic toxicologist told the court that there were low levels of an anti-depressant in Allison Baden-Clay's body.

Monash University's Professor Olaf Drummer said there was not enough of the drug to indicate an overdose.

During cross examination by Baden-Clay's lawyer, Professor Drummer said he could not recall any cases where the drug had caused a person's death, although the court was told that was possible.

Yesterday two detectives told the court that Baden-Clay had been a person of interest since very early in the investigation.

The Crown case is that the 42-year-old estate agent wanted out of his marriage to be with his mistress, and was also motivated by the chance to clear his debts as a result of his wife's insurance payouts.

Yesterday the court was told that Baden-Clay visited two doctors about facial injuries the day after his wife was reported missing.

Both doctors said Baden-Clay was seeking treatment for cuts to his face which he told them were caused by shaving with a blunt razor.

One of the doctors said Baden-Clay also has marks on his chest, which he said were the result of skin irritation caused by a caterpillar.

But an entomologist said he had surveyed the area around the Baden-Clays' Brookfield home and could not find any caterpillar species capable of causing serious skin irritation.

Previous witnesses have told the court that the facial scratches were likely to be caused by fingernails, but DNA could not be obtained from Allison Baden-Clay's nails.