A 94-year-old man has been charged with first-degree murder after police in Florida say he shot dead his 80-year-old wife who had been suffering from dementia.

The Venice Police Department said in a statement that Wayne Juhlin told detectives on Monday night that he had intended to kill himself, but said his gun malfunctioned, and he could not bring his murder-suicide plan to completion.

Juhlin was arrested after calling 911 at around 7.22pm to report his wife's death.

Wayne Juhlin, 94, was arrested on Monday on a premeditated first-degree murder charge after police in Florida say he shot and killed his dementia-stricken wife

Officers who responded to the couple's home at 6000 Aston Gardens Drive in Venice found the suspect's wife, Jacqueline Juhlin, dead of a gunshot wound. Her husband stayed at the scene.

Wayne Juhlin was then taken to the Venice Police Department for an interview.

'The subsequent investigation revealed that the 80-year-old victim was suffering from dementia and her 94-year-old husband decided to end her life by shooting her,' according to the statement from the policy. 'The husband told detectives he intended on turning the gun on himself and taking his own life after killing his wife, but the gun malfunctioned, preventing him from carrying out the suicide portion of the event.'

Juhlin summoned police to his home on Aston Gardens Drive in Venice, Florida (pictured) after his gun malfunctioned, preventing him from taking his own life

Juhlin was booked into the Sarasota County Jail on a charge of premeditated first-degree murder.

He remained jailed without bond on Tuesday. Juhlin's arraignment has been scheduled for November 22.

According to public records, Juhlin was an architect before retiring. His professional license expired in 1992.