WETASKIWIN, Alta. - A father sobbed on the witness stand Tuesday as he recalled how he found his two young children dead in a cold bathtub in the family home south of Edmonton.

Curtis McConnell was testifying at the trial of his former wife, Allyson, who is charged with murdering 2-1/2-year-old Connor and 10-month-old Jayden two years ago.

McConnell said he went to the house in Millet because police had told him his wife had fallen off a bridge in Edmonton.

He said he instantly became concerned for his children. He and Allyson were in the middle of a bitter divorce and she wanted to take the children to her native Australia.

His concern grew when he entered the home.

The TV was blasting.

Inside the master bathroom he found a curling iron and a hair dryer in a tub full of water.

The door to the main bathroom was closed and locked -- strange because they were potty training Connor and always kept it open. The lights were off. He used a butter knife to jimmy his way in.

"I walk in. It smelled like dead bodies," McConnell testified.

"I just dropped to my knees. I reached in. The water is so cold and I could feel something in there. They were so cold and stiff.

"She just left them in there to rot. I had to look away. I don't want to see their dead faces."

McConnell said he pulled the lifeless bodies out onto the floor, then ran to a neighbour's house for help verifying the grisly find.

The defence concedes Allyson McConnell killed the two children. The central issue at trial is her state of mind when she did it.

The Crown says evidence will show Allyson McConnell was angry with Curtis because of the divorce.

The couple married Down Under in 2007 and bought the home in Millet the following year. He worked at a hardware store and she did accounting for an oil company.

Their marriage began to crumble in 2009. Curtis said Allyson became withdrawn.

An agreed statement of facts submitted in court says McConnell drowned the children on Feb. 1, 2010, then drove to Edmonton and parked outside a Toys R Us store. She walked to a hotel and ordered lunch but became upset and left.

She walked to a bridge over Whitemud Drive, one of the city's main freeways, jumped over the railing and fell onto the pavement below. She was treated in hospital for broken legs, pelvis and collarbone.

Investigators found several searches on Allyson's computer relating to suicide and drowning on its hard drive.

"How long does it take to drown?" was one search made a few weeks before the boys were killed, computer expert Dwayne Pilling testified Monday.

"How long does it take to die from strangulation?" was another search made the morning they died.

The woman's lawyer has already told court that his client is suffering from a deep depression and is on a round-the-clock suicide watch.

A judge has already found McConnell fit to stand trial. Her psychiatrist is to be called to testify about her mental state at the time of the killings.