The Henry County State’s Attorney’s office on Wednesday released the results of a four-year cold case investigation into the 1974 murder of an Atkinson teen.

The investigation found that the late Robert G. Clark is likely responsible for Mary Ann Becker’s death.

Clark died at 64 in 2015.

Here is the full news release:

The Henry County State’s Attorney’s office is releasing the following information to update the public on the investigation of the 1974 murder of Mary Ann Becker. The State’s Attorney’s Office remains committed to serving all victims of violent crime and will continue to support area law enforcement with training, tools, and resources to never give up on our unsolved crimes.

In 2013 the Illinois State Police dedicated resources to conduct a comprehensive review and renewed investigation into the 1974 homicide of Atkinson teenager Mary Ann Becker. Mary Ann, age 16, was found strangled in her living room at approximately 11:00 p.m. on September 9th, 1974. A 28 year veteran Illinois State Police Analyst partnered with a local State Police Investigator with the purpose of re-examining all the physical evidence, re-interviewing key witnesses, and looking for opportunities to develop new leads. The results of the 4 year comprehensive investigation yielded a circumstantial case that the late Robert G. Clark is likely responsible for Mary Ann’s death. At age 64, Mr. Clark was found deceased in his Bloomington, Indiana apartment on March 16th, 2015.

On September 29th, 2014, with permission from Mary Ann’s surviving family, investigators along with the Henry County Coroner exhumed Mary Ann’s body from Saint Anthony Catholic Cemetery in Atkinson. An autopsy was performed by Forensic Pathologist Dr. Scott Denton with the hope of collecting physical evidence that would not have been collected in 1974. The results did not produce any new DNA profiles but did discover a previously unknown fracture to her wrist consistent with the violent encounter that took her life. Joel Vandemore of Vandemore Funeral Homes & Crematory graciously provided a new casket, private ceremony, and reburial at no cost to the family. With the financial support of the Henry County State’s Attorney all available forensic evidence was submitted to a private laboratory in Virginia and tested with the most advanced technology available. The results were unsuccessful in developing a full suspect DNA profile.

In the pursuit of new information, Investigators traveled to five States conducting over one hundred interviews with family members, friends, neighbors, co-workers, and current and former Atkinson residents. Investigators sought advice and information from previous detectives that worked the case over the past 40 years. As the investigation progressed, Robert Clark could not be excluded and rose to be the strongest person of interest in the case. Investigators discovered new information contradicting the alibi that Clark was working in the Victoria Coal Mines at the time of the crime. Investigators learned Clark confided in his brother living out of State that he was not working at the time of the murder which contradicts previous information that he had hauled a record number of loads of coal at the mines that evening.

In the summer of 1974, at the age of 24, Mr. Clark lived alone in an apartment within eyesight of the Becker residence. Mr. Clark worked with Mary Ann’s father Tony at the coal mines. Tony had been injured at work and was previously off work for several weeks. Tony’s first day back to work was the evening Mary Ann was killed. Mr. Clark was also very familiar with Mary Ann’s mother’s work schedule and would have known she was working the evening shift at the Atkinson Gulf Plaza Truck Stop Restaurant.

Clark moved out of Atkinson after the murder but remained living in the Henry County area. It wasn’t until 1980 when Clark moved to Indiana after being convicted of raping a 15 year old girl in Galva, Illinois. Clark was sentenced to 6 years in prison however a higher court reduced the charges on appeal and he only served 2 days in the County Jail. The two man investigative team located several people connected to Clark over the years and documented a consistent pattern of violent criminal behavior and mental illness spanning Clark’s entire adult life. Several people from Clark’s past were reluctant to speak about him until they learned he was deceased. By the late 1980’s Clark had been married and divorced three times. During one of many violent attacks against his second wife, Clark reportedly stated he had killed before, and would do it again. Clark threatened to bury her body in the coal mine.

Once all the new investigative leads were exhausted, Investigators briefed the Henry County State’s Attorney and Mary Ann’s surviving family members with the updated information. Upon reviewing the thousands of pages of new interviews, the State’s Attorney believes the circumstantial evidence is strong enough that it would warrant presentation to a grand jury if Mr. Clark were still alive.

Robert G. Clark will forever be presumed innocent as he will never have the opportunity to face a judge or jury in a Court of Law, however, Mary Ann’s family is confident enough the responsible person has been identified they have decided to withdraw their offer of $15,000 for information leading to an arrest and conviction in this case. In an effort to continue gathering information and potential evidence, the Illinois State Police will continue to leave the case open in hopes that the newly released public information will bring in additional calls. Investigators did contact Mr. Clark’s brother in Ohio and received permission to release Robert Clark’s name in this matter.

If anyone has information beneficial to the case please call the Illinois State Police at 309-752-4915 ext 4934 or the Henry County Crime Stoppers at 800-227-2324.