Gleydson Antone "Tony" Costa (August 2, 1944 – May 12, 1974) was an American serial killer and carpenter who achieved notoriety for committing serial murders in and around the Massachusetts town of Truro in 1969.

The case gained international attention when district attorney Edmund Dinis, in comments to the media, claimed "The hearts of each girl had been removed from the bodies and were not in the graves…Each body was cut into as many parts as there are joints." Dinis also claimed that there were teeth marks found on the bodies. These claims produced a stream of national and international media outlets into local Provincetown, Massachusetts.^[2]

The media attention was so great that Kurt Vonnegut (whose daughter Edith had met Costa) compared him to Jack the Ripper in an article in the July 25, 1969 issue of Life Magazine, which was included in his collection of essays Wampeters, Foma and Granfalloons.^[3] Vonnegut maintained a correspondence with Costa. The author said, "The message of his letters to me was that a person as intent on being virtuous as he could not possibly have hurt a fly. He believed it."^[4]

Costa was suspected of killing eight women: Diane Federoff, Bonnie Williams, Barbara Spaulding, Sydney Monson, Susan Perry, Christine Gallant, Patricia Walsh, and Mary Anne Wysocki but convicted of killing only two: Walsh and Wysocki. Although suspected of killing Federoff, Williams and Spalding, those women were later found alive. ^[5] On February 8, 1969, while looking for the bodies of Patricia Walsh and Mary Anne Wysocki, police discovered Susan Perry. Perry had been missing since the previous Labor Day.^[2]

Perry's body had been cut into eight pieces. When Wysocki's body was found about a month later, her torso and head had been buried separately. Not long after, Walsh and the rest of Wysocki's body were found in a forest clearing that Costa had used for growing marijuana.^[2] This "garden" of marijuana plants and the greater case inspired the true crime book In His Garden, by Leo Damore.^[2]

Costa described the murders of Walsh and Wysocki in his unpublished novel, Resurrection, written while he was in prison. In his account, Costa and a friend named "Cory" were out with the two women consuming LSD and Dilaudid. Cory then shot Walsh and Wysocki. Costa claimed he was able to subdue his friend and upon realizing that Mary Anne Wysocki was still alive used a knife to end her suffering. According to Costa, he and Cory buried the bodies.^[6]

The novel also describes the deaths of Susan Perry and Sydney Monzon as due to drug overdoses. Costa claims it was "Carl", his alter-ego, who dismembered and buried their bodies and that he had no knowledge until after their deaths.^[2]

On June 12, 1969, Costa was arraigned on charges of murder for three of the deaths.^[7] In May 1970, he was convicted of the murders of Mary Ann Wysocki and Patricia Walsh and sentenced to life in prison at Massachusetts' Walpole Correctional Institution. Four years after his incarceration, Costa committed suicide by hanging himself in his cell.^[8] In later years, his suicide was questioned as a possible murder.^[9]

The case was covered by the popular true-crime show Born to Kill? in season six. The episode aired on television in 2014.

In 2021, Liza Rodman wrote a book about her encounter with Costa during her childhood. He was her babysitter during summer break before the murders.^[10]

• List of serial killers in the United States