NEW YORK In a reversal suffered by prosecutors at Dr Aafia Siddiquis trial, an American US metallurgical forensic scientist testified on Wednesday that there was no evidence of a high-velocity M-4 gun having been fired during a 2008 confrontation at an Afghan police station in Ghazni as claimed by government witnesses. Dr Aafia, 37, is accused of snatching the weapon and shooting at US army soldiers and FBI agents seeking to interview her two years ago. No one was hit in that incident, but Aafia was badly wounded when a US Army officer shot her. Tobin, who appeared as a defence witness, said that the two holes on the wall of the room that prosecutors say were created when the defendant fired at US interrogators were not from a M-4 rifle bullet, which would have caused extensive damage and left many fragments on the crime. At least the bullets steel penetrator should have been found in the wall, he said. Last week FBI ballistics expert Carlo Rosati, who appeared as a government witness, also made a similar statement, saying he cannot say with certainty that any shots were fired from the M-4 rifle. The only bullets fired at the scene were from the M-9 pistol that a US Army officer used to hit Aafia. Tobin, who made a scientific analysis of the prosecutors evidence, said that the bullet holes in the wall showed no falling damage characteristic of M-4 bullet. When told that eye-witness at the scene had seen Aafia picking up and firing the gun, he said, I pay no attention to such accounts. Im a scientist. Tobin, who was paid $46,000 for his work, said if the rifle was fired at an angle, as was being claimed, the bullet fragments would have hit the ceiling also and left a lot of residue. But nothing was found. He was one of the two witnesses put on the stand by the defences which hoped to wind up its cause by Thursday evening. Closing arguments could come as early as Friday, when the jury is expected to start deliberations to prepare a verdict. The other defence witness was George Michael Newman, a private investigator, who visited Ghazni in December last, to collect evidence at the crime scene. He described the changes that have taken place at the crime scene since that incident. Meanwhile, a demand by prosecutors for allowing Aafia to testify at her trial is causing concern among the members of her defence team retained by the Pakistan government. Experts believe the prosecutors move is aimed at gaining some advantage when their case has considerably weakened because of the inconsistencies in the testimonies of government witnesses. Until now the prosecutors have been asking US District Judge Richard Berman to bar Aafia from the trial because of her courtroom outbursts. But in a sudden move on Wednesday, they now want her on the stand. Lawyers for Aafia had asked the judge to prevent their client from taking the witness stand in the federal court in Manhattan, saying her diminished capacity would result in a painful spectacle. Defence lawyer Charles Swift said the defendant refused to speak with us and runs the risk of prejudicing herself in the eyes of the jurors if she takes the stand. We feel it is our duty under relevant ethical rules to take protective action to safeguard her interests, the letter read. Her family spokesman, Tina Foster, also backed the move by three lawyers retained by the Pakistan government, saying theyre also worried about Aafias mental state. Aafia whom we know and love is not the same rational and focused Aafia who we see in this courtroom, said her brother, Muhammad Siddiqui. In a letter to the judge, the prosecutors changed their stance, saying Aafia had done nothing to forfeit her fundamental right to testify in her own defence. Her more recent outbursts during this trial are neither irrational or delusional, as the defence suggests, but are instead opportunistic and calculated, the prosecutors said. The defendant is an articulate, well-educated, sophisticated person who understands completely the proceedings against her. The judge, who has previously ruled that Aafia was competent to stand trial, was expected to decide whether she can testify on Thursday. At the start of the trial, Pakistans Ambassador to the United States Hussain Haqqani was welcomed by Judge Berman. The ambassador watched the proceedings from the visitors gallery where a special chair was placed for him. Earlier, Haqqani paid a courtesy call on Judge Berman in his chamber. The jury was also shown a more than two-hour video of an interview with a senior Afghan police office Qadeer Khan in Kabul last December, jointly conducted by defence lawyer Charles Swift and the prosecutor. In the more than two-hour long video, Qadeer said he heard three shots from behind a curtain dividing room, but under intense questioning he said he never saw Aafia picking up the rifle. Qadeer, who was stationed in Ghazni in 2008, said police had arrested Dr Aafia, who was looking for her husband there, on suspicion of being a suicide bomber. She was taken into custody, along with her son. But when she tried to escape by jumping put of the window, police tied her hands behind her back. All along she was pleading not to turn her to the Americans. Her hands were freed just before the Americans came to interview her. Qadeer said the items recovered from her purse did not contain any chemicals as alleged by the prosecutors. There were some personal clothing, cosmetics and some hand-written material, he said. Meanwhile, a section of the American press continues to give biased coverage to the trial portraying her as an al-Qaeda supporter and called her Terror Mom even though she is charged with terrorism.