Here we have an instance of the delayed conjoined subject. There are two groups of people who received their trial, “the men of Pachus” and “those kingmen which had been taken and cast into prison”. The longer conjoined subject is delayed, thus allowing for a simpler syntax than the complicated and almost obtuse nondelayed form: “the men of Pachus and also those kingmen which had been taken and cast into prison received their trial according to the law”. As described under 1 Nephi 3:28, the delayed conjoined subject is common in the Book of Mormon text. Also see the full discussion of this construction under hebraisms in volume 3.
Here in Alma 62:9, the typesetter for the 1906 LDS edition accidentally changed the main predicate into a relative clause by inserting who, thus “the men of Pachus who received their trial according to the law”. The result is a sentence fragment. The typesetter was undoubtedly influenced by the relative clause that occurs in the delayed conjoined subject “and also those kingmen who had been taken and cast into prison”. (The copytext for the 1906 LDS edition was the 1879 LDS edition; for Alma 62:9, who had replaced the original which since the 1837 edition.) This 1906 typo was never transmitted into any subsequent LDS edition since the 1906 edition was never used as a copytext.
Summary: In agreement with the earliest extant text, maintain the initial main clause in Alma 62:9: “and the men of Pachus received their trial according to the law”; this clause is followed by the delayed conjoined subject “and also those kingmen which had been taken and cast into prison”.