The Federal Court should discharge and acquit Datuk Seri Anwar Ibrahim from the charge of having sodomised his former aide Mohd Saiful Bukhari Azlan as the prosecution's case was riddled with doubts and unaccounted coincidences, defence counsel Ramkarpal Singh said.

Referring to Mohd Saiful Bukhari's meeting with a senior police officer and the then Deputy Prime Minister Datuk Seri Najib Razak two days prior to the alleged sodomy incident, he said it could not be a coincidence.

He said all the scientific evidence adduced by the prosecution in the sodomy case were unreliable and ought to be rejected at the close of prosecution's case at the High Court level itself.

"The real possibility that the material samples were contaminated and the fact that their (prosecution) description does not match with the history of samples taken, clearly casts a serious doubt on the integrity of the samples.

"It cannot be said without a doubt that they were the same samples retrieved from PW1 (Mohd Saiful Bukhari)," he submitted before a five-man bench chaired by Chief Justice Tun Arifin Zakaria on the seventh day of the PKR adviser's final appeal proceedings.

Ramkarpal Singh also disagreed with the prosecution's contention that it was the defence who proved that there were tampering of samples, especially those collected from the complainant's rectum.

He said even though there was a real possibility of tampering leading to the investigating officer Supt (Retired) Jude Blacious Pereira, the defence could not confront him since it could be someone else who carried out the tampering.

Touching extensively on the testimony by two chemists, namely Dr Seah Lay Hong and Nor Aidora Saedon, Ramkarpal pointed out that the High Court judge failed to appreciate the witnesses' shortcomings in their analysis.

"There would have been no reason to call the appellant (Anwar) to enter his defence since their findings pertaining to 'Male Y' was in doubt," he argued.

(During the trial, Dr Seah confirmed that the DNA profile of Male Y matched the DNA profile of Anwar, which was collected from the appellant while he was under the police custody overnight at the Kuala Lumpur police contingent headquarters).

On the star witness himself (Mohd Saiful Bukhari), Ramkarpal said he was not a convincing witness.

"He could not have been sodomised as there was no evidence that there was a penetration in the first place.

"The fact that the semen was found in his anus cannot, in the circumstances of this case, mean that he was penetrated as there were very serious doubts as to whether that semen was actually retrieved from PW1 (Mohd Saiful Bukhari) on June 26, 2008," he said.

Ramkarpal therefore urged the court not to fall into the prosecutor's fallacy in assuming the DNA evidence was reliable since the defence had succeeded in raising doubt whether there was penetration.

He concluded by saying the appeal should be allowed and the appellant be acquitted and discharged.

On March 7, Anwar, 67, was sentenced to five years' jail for the offence by the Court of Appeal, having been charged with committing it at Unit 11-5-1 of the Desa Damansara Condominium in Jalan Setiakasih, Bukit Damansara between 3.10pm and 4.30pm on June 26, 2008.

The charge, under Section 377B of the Penal Code, carries a jail term of up to 20 years and whipping, upon conviction.