Mumtaz Sattar, 38, from Port Glasgow, Inverclyde, lost her life in suspicious circumstances shortly after arriving in the Punjab with her husband Abdul eight days ago, and may have been throttled, according to a post-mortem examination.
It is now understood Mr Sattar, who has been questioned by police about the death, has made a failed attempt to get travel documents to return to Britain.
Aamer Anwar, the Glasgow solicitor acting on the murder victim family's behalf, said Pakistani authorities have been told he should not be allowed to leave as he is the only witness to his wife's murder.
Mr Sattar said his wife died after the couple had drunk spiked tea before they were thrown out of a taxi they caught from Lahore Airport on September 22.
A post-mortem report carried out in Pakistan found a bone in Mrs Sattar's neck, the hyoid, was fractured. Preliminary findings of Professor Anthony Busuttil, of Edinburgh University, who was asked to review that post-mortem by Mr Anwar said this pointed to someone being throttled.
Mr Anwar said: "My understanding is Mr Sattar's primary concern is to return to this country. And I have said on behalf of Mrs Sattar's family that if he wants his wife's killers to be caught, his primary concern should be to remain in Pakistan and assist the police with all their inquiries, rather than trying to do everything possible to return to this country.
"I don't understand why this man seems to be motivated by simply getting on the next flight home. He is as it remains the only eyewitness to this murder, so it doesn't help anyone if he tries to leave the country."
On Friday, District Police Officer Mumtazir Mehdi of Nankana Sahib Police, the officer in charge of the investigation in Pakistan, said he expected the case to be solved within days.
But Mr Anwar said things have gone on a "go slow" since and has called on the British authorities including the Foreign and Commonwealth Office to become more active in putting pressure on the Pakistani authorities to ensure the family get justice.
The lawyer said: "One of the concerns is lack of resources and also the question of corruption in Pakistan and how it is often the case murders such as this just simply disappear off the radar. So that's why we are trying to keep the pressure on.
"As the days pass, there is a real possibility Mumtaz Sattar's murder will remain unsolved. It is of the utmost importance now that the authorities in this country at the highest levels speak out and seek justice for Mumtaz Sattar. Because at the moment there appears to be silence. And she is a British citizen.
"Unless the Foreign Secretary raises the issue, the Pakistani authorities will not sense any feeling of urgency, will not sense the spotlight on them."
The Sattars, who had been married for 14 years, have two daughters, aged 10 and 13. It is understood they are being looked after by family in Scotland.
A spokesman for the FCO said: "We cannot comment on the allegation we are not doing enough. We are aware of the death of the British citizen and are providing consular assistance to the family."