The trust running mental health services in Herts has been prosecuted following a fatal stabbing at a care home.
Herts Partnership NHS Trust was found guilty of breaching health and safety regulations after a care worker was killed by a patient in Dunstable in 2007.
A joint investigation by the Health and Safety Executive (HSE) and Central Bedfordshire Council found that Abacus House was not the correct care facility for Stephen Flatt, who had been placed there by the trust.
He had been diagnosed with bipolar disorder but staff had no expertise or training for dealing with this disorder, or for managing violent or aggressive behaviour.
In August 2007 Mr Flatt killed Kathleen Bainbridge, 58, with a knife from the kitchen.
HSE inspector Karl Howes said: “This was a tragic incident that left a family without a wife, mother and grandmother. No-one expects to go to work and never return home.
“Care homes have a duty not only to protect the safety of their residents but their staff as well. The trust failed to adequately assess the risks.
“I hope this will make all NHS trusts and care facilities carefully consider the procedures that they have in place during patient placement.”
Sentencing takes place on July 19.