Alleged Shooter Nikolas Cruz Obsessed Over Guns, Violence ... on Social Media

Nikolas Cruz was hooked on weapons and violence ... and that obsession was played out over and over again on his social media pages.

The 19-year-old posed with guns, knives and even bragged about killing a frog on his Instagram account. Cruz is also seen sporting a Donald Trump's "Make America Great Again" hat in another post ... and Cruz allegedly posted pics of shotguns and military-grade rifle bullets on another personal Instagram account.

As we reported ... Cruz participated in at least one training exercise with a white supremacist group.

Cruz -- who 9 months ago threatened to carry out a mass shooting -- is accused of using an AR-15 rifle to carry out the murders. He remained silent while his charges -- 17 counts of premeditated murder -- were read aloud Thursday in court.

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