Lawyers for former North West regional prosecutor Nazir Afzal, whose brother died of coronavirus, wrote to the two forces urging them to investigate further.
They also sent a letter to the Crown asking it to play a “proactive role” in examining the relevant evidence.
Afzal, who has previously threatened to initiate private prosecutions on behalf of the public, said, “I fear that the police and prosecutors have not received all the relevant information and that their decision-making is therefore incomplete. .
“I am troubled that previous correspondence from people, including members of Parliament, has gone unanswered. As a result, public confidence is compromised.
“We have already had new information from reliable sources that reflect poorly on all those who have examined the allegations so far, including the likelihood of other relevant events. ”
Public confidence in the government has been shaken as a result of Mr Cummings’ actions, but the Prime Minister has backed his senior adviser in the case despite calls from Conservative MPs to step down.
In their letter to the Durham police, Mr. Afzal’s lawyers wrote: “We understand that you have undertaken a short and close investigation into three issues and have given your opinion on whether they constituted a violation of the regulations.
“However, it appears that not all of the relevant evidence regarding these issues has been gathered. In addition, a number of other alleged breaches of the Durham settlements do not appear to have been investigated. ”
The three cases are said to be references to Mr. Cummings ‘self-isolation at his parents’ home near Durham, a day trip to Barnard Castle during which he claimed he was “testing his eyes And a second alleged visit to the Northeast. April 19.
The Durham Constabulary discovered in June that the senior advisor may have broken the lock rules but decided to take no further action
Lawyers Hodge, Jones and Allen also wrote to Met police asking them to investigate his actions in London, which do not appear to have been reviewed by Durham forces.
Mr. Cummings denied any wrongdoing and refused to apologize for at least breaking the spirit of the guidelines that millions of Britons have rigidly followed
No. 10 declined to comment.
A Metropolitan Police spokesperson said, “Of course, the MPS will not retrospectively investigate matters related to the orientation of Covid. “