Abdul Sattar, 45, and some alleged accomplices appeared before Nankana Session Court yesterday in connection with her death, more than three months after his wife, 38, lost her life in suspicious circumstances.
A post-mortem examination indicated Mrs Sattar from Port Glasgow, Inverclyde, may have been throttled after arriving in the Punjab. However, her husband said she died after the couple had drunk spiked tea before they were thrown out of a taxi they caught from Lahore Airport.
Aamer Anwar, the Glasgow solicitor acting on behalf of Mrs Sattar's family, said there were fundamental concerns that basic forensic and investigative steps had not been followed by the Nankana Sahib Police, which jeopardised the case.
He also said that as part of the investigation Police Scotland's DCI Jim Kerr uncovered a "turbulent history of sustained and brutal violence by Abdul Sattar towards his wife" over their 14-year marriage.
"Various requests for information and offers of assistance by authorities and my firm were made to the Punjab police that were routinely ignored," said Mr Anwar.
"Furthermore, serious allegations were raised of bribery and corruption of the officers involved in investigating the case. Despite this, no inquiry took place into their actions. I even have a recording of officers asking witnesses to lie. Despite the arrests of the accused matters appeared to grind to a halt.
"I believed, at best, that Nankana Police were being incompetent and, at worst, had deliberately tried to sabotage a successful prosecution.
"It was clear to me I would have no option but to travel to Pakistan and for my firm to take matters into their own hands."
He has now instructed two of Pakistan's leading criminal advocates, Mrs Bushra Qamar and Humd-ur-Rehman Waseem Zafar, to assist in conducting the prosecution against Abdul Sattar and his alleged accomplices, believing police failure to investigate would lead to "a failure" in the state prosecution.
The team are preparing to indict investigating officers for "dereliction of duty".
Following yesterday's court appearance, the case was adjourned until January 21, to allow for more time to prepare a private prosecution - outwith the hands of the State.
"We now intend to frame within the final charges that the investigation officers were incompetent and a defective investigation was carried out," said Mr Anwar. "The police were bound to collect evidence but failed to do so and is now liable for prosecution under Pakistan Police Order 2002 for defective investigation.
"They never even went to check, like I did today, the tea shop where poisoned tea was allegedly made. It would have confirmed the shop shut at 11pm - at least three hours before the Sattars' car would have passed.
"This is the first time Scottish lawyers have been involved in the prosecution of a murder in Pakistan and we are determined to pursue justice for the family of Mumtaz Sattar.
"We now are acting in the unique capacity as prosecutors and will require the full assistance of Police Scotland and the authorities in Pakistan. We would hope the accused can be brought to trial within six months."
The legal team has met a series of Pakistan government ministers, as well as former Glasgow MP Mohammad Sarwar, now Punjab governor, to raise their concerns about the case. Mr Sarwar recently said the government would be looking "very seriously" at how to protect the rights of overseas Pakistanis and ensure their security.
Mr Anwar also met senior High Court judges Justice Manzoor Ahmad Malik and Mansoor Ali Shah to "raise concerns with the judiciary as to the actions of the police and to ensure justice is done".
The concerns over the conduct of the case come as family and friends of Scots-based businessman Saif Rehman, 31, and his American wife Uzma Naurin, 30, who were murdered in the Punjab two years ago, said they had all but given up hope of getting justice because of police corruption.