LAHORE, Jun 22 : A Christian organisation in Pakistan on Monday demanded an investigation by a High Court judge into the killing of a Sikh couple inside a gurdwara in Khyber Pakhtunkhwa province after it was revealed that a police official was involved in the crime.

Sikh couple -- Jagannath Singh, 70, and his wife Asma Wanti, 69 -- serving as caretakers of a gurdwara in Mardan district, around 60 km from Peshawar, were shot dead by police constable Sher Shah last Wednesday

Shah had performed security duty outside this gurdwara for several months in the past.

"As the suspect happened to be a police official, the investigation into the murder of the Sikh couple in Mardan should be conducted by a high court judge to ensure transparency and the public should be informed of the facts," Pakistan Masiha Millat Party head Aslam Pervaiz Sahotra said in a statement.

He said the brutal killing of an innocent and unarmed Sikh couple is a highly condemnable act, and merely arresting the suspect and sending him to jail is not sufficient.

"Identifying the administrative mistakes and weaknesses that contributed to the occurrence of this incident and taking action against those responsible is also the duty of the government," Sahotra said.

Pakistan's Punjab Minorities Minister Sardar Ramesh Singh Arora has urged the Khyber Pakhtunkhwa government to uncover the motives behind the brutal murder of a Sikh couple and to ensure the protection of minority communities and their places of worship throughout the province.

"Khyber Pakhtunkhwa police should also assess the mental state and attitudes of its personnel to help prevent such tragic incidents in the future," Arora said.

Arora, who is Pardhan of Pakistan Sikh Gurdwara Parbandhak Committee, had also attended a prayer ceremony organised by the Sikh community at a gurdwara and met the daughter of the deceased couple to express his condolences.

He said that a significant Sikh population once lived in Khyber Pakhtunkhwa, but their number has steadily declined due to various circumstances.

Arora demanded that the individuals holding extremist views should be kept away from minority places of worship.

He also demanded complete security for the family members of the deceased Sikh couple and for those who played a role in registering the case.

Earlier, addressing a press conference, Mardan District Police Officer (DPO) Masood Bangash said the suspect had previously been deployed on security duty at the same gurdwara for about 15 months, nearly three years ago.

The DPO said the suspect was traced with the help of CCTV footage and was arrested while wearing the same clothes he had on at the time of the incident.

Initial investigations suggest that the suspect acted on the basis of his personal beliefs and hardline views, Bangash said.

He said the suspect's father is also employed in the police department.

According to the DPO, on the day of the incident, the suspect entered the gurdwara and proceeded to the upper floor, and opened fire on the Sikh couple.

The police officer said the elderly couple lived on the second floor of the gurdwara and was responsible for its upkeep and management.

The gurdwara, known as Dera Hoti Wala Baba Karam Singh, is a historic structure in Mardan dating back approximately 150 years. (PTI)