Citing a "pattern of prosecutorial misconduct," Judge Merna B. Marshall yesterday dismissed all charges against Robert (Reds) Wilkinson in connection with the 1975 Santiago firebombing.

The decision in Common Please Court came 20 months after Wilkinson had been charged with five counts of murder in the racially motivated firebombing, which killed a Puerto Rican woman and four children. Wilkinson, who was convicted a year ago, spent 15 months in jail. He was released last December after another confessed that he had committed the crime.

"Had the . . . facts been known as they are known today," the judge wrote, "there is no doubt that the defendant would have been acquitted."

Judge Marshall said that there was no evidence to justify a retrial, which was being sought by District Attorney Emmett Fitzpatrick. Under the terms of her decision, Wilkinson can never be rearrested for the firebombing.

In addition to prosecutorial misconduct, the judge said there were several other reasons for dismissing the charges. She said new evidence had shown that Wilkinson was innocent. Further prosecution, moreover, would "violate both the state and federal constitutional provisions against double jeopardy and . . . constitutional privileges of due process," she said.

Fitzpatrick, who could not be reached for comment yesterday, can appeal Judge Marshall's opinion to the state's Supreme Court. Assistant District Attorney Clifford Haines, who has supervised the handling of the Wilkinson case, said his office would study the judge's ruling before deciding whether to appeal.

Asked about the judge's findings of prosecutorial misconduct, Haines said he had no comment.

The misconduct in the Wilkinson case, Judge Marshall said, was the fault of the district attorney and not the police. The police acted reasonably in arresting Wilkinson because a witness had said at the time that he saw Wilkinson throw the firebomb, she said.

Earlier this year, two men, David McGinnis and Ronald Hanley, were convicted of the firebombing in federal court. McGinnis testified that Wilkinson had had "absolutely no involvement" in the crime.

Judge Marshall made her decision after holding six weeks of hearings on a motion by Wilkinson's attorney to have the charges dismissed.

"Testimony during the course of this hearing," Judge Marshall wrote, "suggests a 'seat of the pants' prosecution. The trial attorney (David Berman) at one point claimed he did not know which statements were turned over to the defendants. Some of the misconduct may of course be attributable to negligent or shoddy trial preparation."

The Inquirer reported in December that on the day of the firebombing, homicide detectives had beaten, threatened or otherwise coerced seven persons to force them to sign false statements implicating Wilkinson. By the end of the interrogations, Wilkinson, who is slightly retarded, had signed a "confession" to the killings.

Wilkinson has consistently maintained since that day that he did not commit the crime and that police made up the "confession."

(The judge did not hear any testimony about beatings or coercion in interrogations by police.)

Wilkinson's conviction was overturned in late December when the state's only eyewitness, Nelson Garcia, admitted that he had lied in testifying against Wilkinson at his trial in April 1976.

Judge Marshall said yesterday that the district attorney's office had acted improperly during the trial by failing to give to defense lawyers a statement that Garcia had given police shortly after the firebombing.

"The . . . Garcia statement was critical," Judge Marshall wrote. "In the hands of a skilled attorney it could have been used to demonstrate that the witness (Garcia) was suggesting that the accused threw the bomb with the weaker hand and thus raise a reasonable doubt as to whether the witness saw the accused throw the bomb at all."  (In that statement, Garcia said that Wilkinson, who is righthanded threw the bomb with his left hand.)

In recanting his testimony in December, Garcia admitted that he had not, in fact, witnessed the firebombing.

Judge Marshall also criticized the district attorney's office for its handling of the Wilkinson case after the trial. She said the prosecutors had acted improperly in withholding two statements taken by police a month after the firebombing. In those statements, Joseph Smith and Arlene McGinnis told investigators that Hanley and McGinnis were the actual firebombers, and that Wilkinson was innocent.

Defense attorneys Robert Matthews and Jack Levine did not see those statements until March 14, 16 months after Wilkinson's arrest.

Judge Marshall did not say whether she believes the district attorney's office had intentionally withheld the evidence. She wrote, however, that "the failure to handle these statements properly again demonstrates a certain insensitivity to the rights of the accused."

Judge Marshall also questioned the major new piece of evidence against Wilkinson presented by the district attorney for the first time on March 3. On that day, Haines said that Wilkinson had confessed to the crime to Detective John Ellis, who directed the police investigation. Haines said Wilkinson had made the confession in an elevator at police headquarters just after his interrogation.

"(This statement was) the only showing of evidence beyond the evidence brought out at trial," Judge Marshall wrote. "The fact that (it) was not brought to the defendant's attention previously as directed raises another point of prosecutorial misconduct.

"The fact that it had not been used at the first trial . . . and apparently (was) not even part of the prosecutor's file shrouds the statement in such suspicion as to all but destroy its probative value."

"Despite the prosecution's opportunity both at trial and at this hearing to make a showing that it had a reasonable expectation of obtaining a supportable verdict . . . it could not do so," Judge Marshall said, ". . . A pattern of prosecutorial mishandling permeated the defendant's trial . . .

"To do other than terminate these proceedings . . . would relegate this court to a degree of uselessness . . . In the interests of justice, the further prosecution of the instant case should be terminated and the indictments dismissed."

Because of the way the case has been handled, Wilkinson's attorneys have filed a civil suit in federal court seeking monetary damages from the city.

The suit charges the district attorney with malicious prosecutor and charges the police with beating Wilkinson during his interrogation.