Alabama Teen Fights Woman on Video After Alleged Mallet Murder of Grandma

The cops didn't have a hard time solving the murder of a grandma in Alabama ... 'cause her granddaughter confessed to it all on video!

Here's the scoop ... a security camera attached to a house in Irvington, Alabama, recorded 18-year-old Jailen Mia Lupton dashing onto a porch and getting into a fight with her neighbor, Cheryl Edwards, WDHN News reports.

During the altercation, Lupton bluntly tells Edwards she just killed her grandmother ... which only serves to escalate the situation, according to video obtained by WDHN.

Edwards desperately tries to push Lupton off the porch and starts hitting her with a mop. Lupton runs away, but then comes back and barges into Edwards' house after she goes inside. Edwards then flees from her home while screaming for help.

Police were notified and arrested Lupton for the July 26 murder of her grandmother -- 70-year-old Diane Trest -- as well as burglary for breaking into Edwards' home.

According to local media, Trest was found on the front lawn of her residence with trauma to her head and a mallet lying nearby. It's unclear what the motive was ... but Lupton and Trest reportedly had a rocky relationship.