Dad learns kids are dead via voicemail after long-haul flight

Warning: This article contains details some people may find distressing.

A US man has described the devastating moment he learned his children were dead.

Kevin Krim, 42, landed at JFK Airport in New York after a business trip on October 25, 2012. The media executive switched on his cellphone and was greeted by a flood of text messages and missed calls.

As he read through the messages, two policemen escorted Mr Krim to the plane's cockpit. It was then that he pressed play on a voicemail message from his wife, Marina.

It contained the worst possible news.

"I pressed play to listen to it, and I just heard the background noise of screaming," he told a New York court on Tuesday. "I crumbled to the ground."

The Krims' two young children, six-year-old Lucia and two-year-old Leo, had been stabbed to death by their nanny.

Yoselyn Ortega is currently on trial for the murders of the children. The 55-year-old Dominican woman faces two counts of first-degree murder and two of second-degree murder, but has pleaded not guilty by reason of insanity.

The court heard Mr Krim's heartbreaking testimony on Tuesday, as well as the horrifying details of how the children died.

On the day of the killings, Mrs Krim returned home to the family's Manhattan apartment to find Lucia and Leo's bodies in the bathtub. Ortega stabbed herself in the neck as Mrs Krim came through the door, but survived her injuries. 

Ms Krim testified earlier in the trial, saying she came home to a "total horror movie".

Last week a juror had to be excused from the trial because he said he could no longer make an impartial judgment after seeing the gruesome crime scene photos. 

Ortega has admitted to killing the children, but says the devil made her commit the crime.

The Krims hired Ortega in 2010 when Mrs Krim was pregnant with Leo. Mr Krim told the court that they offered her extra cleaning work and paid for her flights home to the Dominican Republic as they knew she was struggling financially.

He said neither he nor his wife ever suspected Ortega was capable of such an act.

The couple have three other children, two of whom were born after the deaths of Lucia and Leo.