Craig W. Conkey speaks to the judge in Grafton Superior Court, Friday, Feb. 14, 2014 in North Haverhill, N.H. Conkey man convicted of killing two women in Massachusetts pleaded guilty Friday to stabbing Theresa Reed, a 30-year-old New Hampshire woman to death in 1991. At left is Conkey's attorney, James Brooks. (AP Photo/Valley News, Jennifer Hauck)
Craig W. Conkey spoke to the judge today in Grafton Superior Court in North Haverhill, N.H.
Jennifer Hauck/Valley News/AP

A man previously convicted of killing two women in Lexington in the early 1990s admitted to stabbing a New Hampshire university employee to death in 1991, according to an official from the New Hampshire Attorney General’s office.

Craig W. Conkey, 47, pleaded guilty today to first-degree murder in Grafton County Superior Court. He was sentenced to life without parole, said Jeff Strelzin, chief of the homicide unit at the attorney general’s office.

Conkey stabbed 30-year-old Theresa Reed to death in her Plymouth, N.H., apartment a week after the fall semester started in 1991. Reed was an assistant registrar at Plymouth State University. She was found with nine stab wounds, said Strelzin.

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Conkey is already serving two life sentences in Massachusetts after being convicted of killing two women in Lexington in 1992 and 1994.

On Aug. 23, 1992, he stabbed Kathleen Dempsey 17 times after breaking in to her apartment. Twenty years later, he pleaded guilty to second-degree murder in July 2012, and he was sentenced to life in prison.

Conkey had earlier been convicted in the murder of Mary Lou Sale. She was found dead in her apartment on Dec. 6, 1994. She had been beaten, strangled, and sexually assaulted.

Conkey came forward and implicated himself in the Dempsey murder while he was in prison for the Sale murder, his defense attorney has said.

Also in 2012, Conkey contacted New Hampshire officials and said he was connected to an old killing — the Theresa Reed murder, which led to his conviction today.