One Prosecutor later heavily in debt and fled the country:
One of the Counsel for the Prosecution that helped convict Palmer was Mr. Edwin James, Q.C. James was also the prosecuting counsel who lost the case brought against Mrs. Sarah Palmer, at Westminster, when William Palmer said that his wife Annie had forged his mother's signature. Five years later James was a Member of Parliament but like Palmer got into financial difficulties and was disbarred for fraud with amounts of over £60,000. But when he got in to trouble he was able to flee the country leaving debts of £100,000. Once in New York he was not only able to to continue his legal work but also became a became a successful actor performing at the Winter Garden Theatre. He later returned to England where he died, poor, in 1882 aged 70.

A picture of Sir Alexander Cockburn from The Trial of William Palmer (from the Notable Trials Series) Second Edition revised by Eric R. Watson published in 1923.

Serjeant Huddlestone Defects to the Prosecution:
Serjeant Huddlestone had been asked to defend Palmer and had, in fact, appeared for Palmer in the successful bid to have the trial switched to London and in January 1856 had successfully appeared for Mrs. Sarah Palmer at the Westminster and had represented Samuel Cheshire when he was tried for opening mail addressed to the coroner. However very late on he changed to work for the Crown in prosecuting Palmer. Surely this must have harmed Palmer's case.

Mr. Welsby:
I can find no information about the fifth member of the Prosecution Team.

The Counsel for the Crown

Mr. Huddlestone Q.C.     Mr. Bodkin,      Mr. Welsby
The Attorney-General,     Mr. Edwin James Q.C.
From the Times Report of the Trial of William Palmer, published 1856

The Powerful Attorney-General determined to hang Palmer:
Attorney General was unrivalled at the time as an orator. He started the prosecution in hushed silence and delivered a masterly display of oratory as he set out the background to the charge of murder. He held the attention of the courtroom for nearly four hours. He did not miss one point and set out, with admirable clarity, the case against Palmer. It was said that he eclipsed even his most notable performances.

If this was not enough on the tenth day of the trial, his closing speech lasted six hours and he spoke for all that time without referring to any notes. Fletcher in his 1925 book, described his masterly closing speech as, "tightening the rope round Palmer's neck with every detail, and tearing to pieces the weak defence which had relied mainly on the medical aspects of the case, and showing completely how the crushing circumstantial details had ALL remained unanswered".
Robert Graves in his 1957 book claimed that the Attorney-general had a personal grudge against Palmer. On the evening after the second day of the trial the Attorney-General, who enjoyed betting on the horses, dined with some racing friends and was told by one of his guests Frank Swindell that he thought that Palmer had tried to "doctor him to death" at Wolverhampton Races.