To the best of my recollection, the next day this expert was sworn in. He was wearing a trench coat or something from Central Casting and was blathering on about the blood spots found on the jacket of one of the suspects. Suddenly with great drama he reached into an inside coat pocket and with great flourish brought out a magnifying glass. At this point most of us had a hard time keeping from laughing at the remainder of his presentation thinking we were suddenly seeing part of a Pink Panther movie; perhaps he saw one on the plane from wherever he came from. Now I assure you that no judgement was harmed by this action.
After a few more witnesses and closing arguments it was about time for deliberation. The judge gave us our instructions which included long explanations of the various degrees of homicide, the meaning of reasonable doubt, deliberate premeditation, and the explanation of joint venture. It was interesting to hear that premeditation could be almost spontaneous right at the scene and didn't require serious prior planning. Later we were given a typed copy of this explanation which was very helpful to us. The judge appointed a foreperson, and pulled a name out of a hat and the 13th juror (recall that the other 3 had been removed) was named as an alternate and prohibited from participating in the deliberation. We saw him in the jury room at break times and at the hotel, but of course we weren't allowed to talk about the case.
During the 5 weeks of testimony we had heard a large amount of witnesses. We had police at the arrests, police investigators, a number of witnesses who had seen the defendants just before and during the crime, some people who had encountered them earlier during the day, several people giving background about the victims, a few character witnesses for the defendants. We were not allowed to take notes so this was a lot to remember and decipher.
Some of the police and other officials gave very good clear testimony, but some of the others were pretty fuzzy. Interestingly enough several years later I met the new Cambridge Police Commissioner at a meeting soon after he had gotten started. One of the things I remember him saying was that when he arrived there was one computer available for officers to use in the department and not even many typewriters and the process for their recording notes was pretty weak.
The judge (Wendy Gershengorn) seemed very fair and skilled at her job. At various times she would explain things that had happened in the court to the juror which was extremely helpful to us. She didn't have an easy time because of the presence of four defendants each with his own attorney.