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A Florida man has been charged with murder in the death of a transgender woman who was found fatally shot in a Tampa park last week, authorities said.

Keith Gaillard, 18, of Tampa, turned himself in to the Hillsborough County Sheriff’s Office and was charged Tuesday with one count each of first-degree murder and possession of a firearm by a “violent career criminal,” the sheriff’s office said.

India Clarke appears in an image from her Facebook page. via Facebook

India Clarke, 25, was found dead at around 8:45 a.m. on July 21. She suffered a single gunshot wound to the head, the sheriff’s office said.

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The sheriff’s office did not release a motive in the killing, but said investigators believe Gaillard knew the victim.

RELATED: Transgender Women Murder Victims More Likely to Be Black of Latina

Detectives found a fingerprint on a cigar wrapper inside Clarke’s car, and Gaillard’s public Facebook profile allegedly showed him showing off a small-caliber revolver, the sheriff’s office said.

A witness told investigators that Gaillard had a .22-caliber revolver, and that he told the witness, "I think I killed someone," according to the sheriff’s office. Another witness allegedly told investigators that Gaillard said, "that was me," when asked about the body found the park, the sheriff’s office said.

Online court records do not list an attorney representing Gaillard. A phone number for Gaillard’s family could not immediately be found.

Caitlyn Jenner, the Olympic champion formerly known as Bruce Jenner, wrote about Clarke in a blog post published Wednesday.

Jenner has highlighted violence against transgender people since she publicly announced her new identity in Vanity Fair in its July issue, and she spoke about the issue in a speech while accepting the Arthur Ashe Courage Award at the ESPY Awards in Los Angeles earlier this month.