The DPD arrested and charged LHO for the murder of JFK based upon the evidence that they had available on Nov. 22. This act confirms that they believed they had sufficient evidence to do so as of that time.
And we should care what the DPD "believed", why, exactly? They apparently "believed" that they even had probable cause to arrest him for murder in the theater with NO EVIDENCE WHATSOEVER.
Oswald is then murdered two days later meaning there would never be a criminal prosecution. Thus, the DPD would have no incentive to then fabricate any additional evidence to bolster the prosecution of Oswald for that crime.
'I just don't believe there was ever a print,' said Drain, He noted that there was increasing pressure on the Dallas police to build evidence in the case. Asked to explain what might have happened, Agent Drain stated, “All I can figure is that it (Oswald's print) was some sort of cushion, because they were getting a lot of heat by Sunday night. You could take the print off Oswald’s card and put it on the rifle. Something like that happened.” -- Henry Hurt , "Reasonable Doubt", p. 109
It is incredibly risky to fabricate evidence in any murder case and a crime much less the crime of the century.
And yet that is exactly what the Dallas PD did in the case of Randall Dale Adams.