Persons of Interest
One of the first to be questioned by police was Tony Jackett because his relationship with Christa could have destroyed his marriage, which investigators believed was a motive to kill. Also, Christa was trying to obtain child support from him that could have put a considerable financial strain on his family.
But Tony repeatedly denied having anything to do with the murder and explained to police that his wife already knew about the affair at the time of Christa's death and had forgiven him. Moreover, he was willing to formalize the parenting agreement, meaning that he recognized Ava as his daughter and was willing to provide child support, Harriet Ryan reported. But, the main thing that vindicated Tony was the fact that his DNA didn't match that taken from the crime scene.
Once Tony was no longer a person of interest, investigators then turned their attention to Tim. He was likely suspected because he once dated Christa and even lived with her briefly before she ended the relationship. The break-up could have been seen as motive enough to kill. According to Richardson, Tim also had brain surgery shortly before the murder, which could have caused investigators to question if he was mentally stable at that time.
Tim, who professed his innocence from the beginning, was keenly aware that he was a key suspect in the murder case and was deeply troubled about it. Richardson stated that Tim was so distressed by the investigation and the murder of his friend that he even contemplated suicide, resulting in his being hospitalized for a brief period. It was a relief when investigators learned that his DNA didn't match the DNA obtained from the crime scene.
Police also had their eye on was Elizabeth Porter, 29, the girlfriend of Christa's father. Elizabeth was a known heroin addict. Christa believed she was sponging money off her father, Jessica Heslam reported in the Boston Herald. One theory is that Elizabeth could have been manipulating Christa's father, who was co-executor of the estate and trust fund his daughter was to inherit, in order to get the money for herself, United Press International suggested. If so, it could have been a motive enough to kill.
Elizabeth also caught investigators' attention because she had been previously linked to another murder case a little more than a year before Christa's death. At one point, Elizabeth had offered sexual services to Dirk Greineder, a Boston allergist, who was later convicted of killing his wife. Elizabeth was a key witness at the trial but was never implicated in the actual murder.
Even though Elizabeth had a troubled background, investigators in Christa's case just couldn't find enough evidence to link her to the murder. The fact that the evidence found at the crime scene suggested a male attacker eventually led to Elizabeth's exclusion as a suspect. Thus, investigators were forced to look elsewhere. One of the places they hoped to find answers was in the state crime laboratory in Sudbury, where DNA samples were sent and processed.