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The FBI has joined the investigation into the fatal stabbing and dismemberment of a 40-year-old woman inside Atlanta's Piedmont Park early Wednesday.

Katherine Janness was walking her dog in the park Tuesday evening when she was brutally attacked.

Janness' lesbian partner pinged her phone and located her spouse's body inside the park.

Janness' body parts were found scattered about 100 yards inside the Charles Allen Drive entrance to the park near 10th Street in Midtown just after 1 a.m. Wednesday. Her dog Bowie was also stabbed to death.

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Bowie defended his owner during the vicious attack. FBI agents plan to use DNA from the dog's saliva to identify the killer.

Atlanta police have stepped up foot patrols inside the park since the "gruesome" murder.

Police are trying to determine if Janness' murder was random or targeted because the killer spent time with her body after she died.

Investigators aren't ruling out a serial killer. Janness is the second woman killed at an Atlanta area park in the past week.

Police are asking residents who live on 10th Street near the park to check their security videos.

Janness worked as a bartender for Campagnolo restaurant in Midtown Atlanta.

A $10,000 reward is being offered by Atlanta Crime Stoppers for information on the case.