This is the harrowing moment a former model and Miss Guatemala contestant was shot through the back of the head in broad daylight.

Rosa Otilia Ramirez, 32, was killed at 7am on January 19 in Guatemala City as she walked home after dropping her daughter off at school.

CCTV captured Ramirez' final moments as she strolled along the pavement, unaware that a masked assassin was following her.

Rosa Otilia Ramirez, 32, was shot dead in an assassination in Guatemala City at 7am on January 19 as she walked home after dropping her daughter at school

Police say Ramirez was killed by somebody who knew her in what was likely a 'crime of passion', but have not made a single arrest or named a suspect

He can be seen reaching into his waistband and pulling out a handgun before quickening his step to catch up to her.

Before Ramirez can even raise her head to check who is approaching he fires a single shot through the back of her head.

She can then be seen crumpling to the floor before the man flees back in the direction he came.

As Ramirez' body lies on the pavement, cars can be seen driving past on the street as people make their way to work.

The footage was broadcast by Guatemalan media as police appealed for information on the brutal killing.

Police say the killer knew Ramirez and it was likely a 'crime of passion', though have not named a suspect or made a single arrest.

CCTV broadcast by Guatemalan television stations shows Ramirez walking along the street as cars drive past, unaware a masked assassin is following her

The man can be seen reaching into his waistband and pulling out a gun before running up to the former Miss Guatemala contestant and firing once through the back of her head