what does the last sentence mean?
Accuracy was not a forte of official Dallas that afternoon. On the new document—the deceased's "usual occupation" was given as "President of the U.S."—Kennedy's Washington address was erroneously recorded as 600, not 1600, Pennsylvania Avenue. The transit permit incorrectly listed his age as forty-four. The Dallas Police Department completed a homicide report later in the day and it, too, was imprecise, stating that headquarters had received word of the shooting at 5:10 P.M. With that the local rites were over. Ceremonial homage had been paid to the letter of the law.

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Answer

This means that the police officers filling out the report did the absolute minimum required by the law.

"Letter of the law" means the exact thing that a law says.  You can contrast this with "spirit of the law" which is what the lawmakers were intending when they wrote the law.  Here the letter of the law says that police must write a report for a crime, so the police did so.  But they did not put any extra effort in, so they only followed the letter of the law, not the spirit.

"Ceremonial homage was paid" is used a bit sarcastically here.  "Pay homage" means to give respect to or to revere someone or something.  This is simply emphasizing that the police only did the bare minimum and followed the letter of the law exactly.

Answer

The word you need is "pay homage". It has many meanings. Look it up and I'm sure you'll understand it.