A strange purple glowing UFO with three rear lights that was filmed by a family is being investigated by paranormal researchers.

The couple and their son thought it might have been a military drone, but said they dismissed this theory when it suddenly spun and disappeared.

The case has been taken on by the Mutual UFO Network (MUFON), which is the world's biggest alien investigation organisation, based in the US.

The footage was recorded this month over Cumberland County, Maine, from the family’s home at 9.23pm local time.

In a report to MUFON, the unnamed father said: "My wife looked out the window and saw an object with bright light high in the sky.

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