LOS ANGELES (CBSLA.com) – The wife of a Woodland Hills hairstylist and a convicted sex offender she was having an affair with have been arrested in the murder of her husband, Los Angeles police announced Friday. A third suspect remains at large.

Forty-five-year-old Monica Sementilli and 55-year-old Robert Baker of Canoga Park were arrested Wednesday on first-degree murder charges in the January stabbing death of 49-year-old Fabio Sementilli.

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Fabio and Monica Sementilli.

Sementilli and Baker were believed to have carried on an affair for about 18 months prior to Fabio’s killing, LAPD Capt. William Hayes told reporters in a news conference. Investigators suspect that money was a motive in the murder. Fabio had a $1.6 million life insurance policy, police said.

Baker is a registered sex offender. In 1993 he was convicted in Long Beach for lewd and lascivious acts with a minor, Hayes said.

Fabio Sementilli was found dead Jan. 23 on the back patio of his home in the 5000 block of Queen Victoria Road. He had been stabbed several times in the face, neck and upper body, police said. His 2008 Porsche 911 Carrera was also missing.

Investigators believe that Baker and another man — who currently remains at large — carried out the murder, which was orchestrated by Monica. Two men, one believed to be Baker, were seen running from the home on the night of the killing, police said.

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Hayes said investigators have confirmed Monica’s whereabouts on the night of the murder, and believe she was nowhere near the home.

Monica and Fabio were still married and living together at the time of his death, Hayes said. On Sunday, three days prior to her arrest, Monica accepted a lifetime achievement award on her deceased husband’s behalf.

Police did not have a detailed description of the outstanding suspect because he was wearing a hooded sweatshirt. He was only described as between 5-foot-5 and 5-foot-7 with a stocky build.

Monica and Baker were set to be arraigned Friday in Los Angeles Superior Court in Van Nuys.

Sementilli was Vice President of Education for Wella, a major German hair-care company.

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Anyone with information on the third suspect or the case in general is asked to contact LAPD.