A father accused of killing his daughter was caught on surveillance video loading his revolver at a gas station the day before the shooting, a court has heard.

Jamal Mansour, 64, from Rocky River, Ohio, has pleaded not guilty to aggravated murder and other charges stemming from the shooting of 27-year-old Tahani Mansour on September 27 in their family home.

The father, a wealthy businessman, told a judge after his arrest that the shooting was accidental, however prosecutors argue the footage of him loading the weapon proves he had a 'calculated plan'.

Jamal Mansour (pictured left), a 64-year-old father accused of killing his 27-year-old daughter, Tahani Mansour (right), was seen loading a revolver at an Ohio gas station before the shooting, a court heard

Court records indicate Mansour said he shot his daughter 'out of anger'. Authorities haven't released further details about a potential motive.

Prosecutors allege Mansour shot his daughter three times in the head, once from just one-foot away, Cleveland.com reports.

The 27-year-old was found in her bed.

During an arraignment hearing in September, Rocky River Prosecutor Michael O'Shea described the killing as an 'execution'.

The prosecutor's description of the killing has raised the suggestion that it might have been an honor killing, but the suspect's attorney, Angelo Lenardo, vehemently denied it, saying the very notion was 'racist and offensive.'

The youngest of six children, Tahani was described by friends as bright and energetic, and had recently been hired as a clinical pharmacist by the Cleveland Clinic.

She received a doctor of pharmacy degree from Northeast Ohio Medical University in 2013, worked as a clinical pharmacist for University Hospitals and taught at the University of Findlay and the medical school, according to her LinkedIn account.

Mansour, a married father-of-six and a grandfather, moved to the U.S. from Jordan in 1978, and owned several stores across Ohio.

Crime scene: The 27-year-old clinical pharmacist was fatally shot in her upstairs bedroom at the family's home in Rocky river (pictured)

Records show that Jamal had previously threatened to commit suicide over Tahani's work-related trip to Las Vegas.

The station WOIO obtained a police report dated December 1, 2012, saying that someone had called the authorities saying that Jamal had threatened to take his own life if his daughter failed to return home from a conference in Las Vegas by 7am the next day.

Police officers performed a welfare check on Jamal, who denied ever threatening to harm himself but confirmed that he was upset with Tahani for going to Las Vegas.