An investigation into alleged police computer misuse by Dyfed-Powys' chief constable has been dropped after his sudden retirement, it has emerged.
But a claim of financial irregularities against Terry Grange is being examined as a potential criminal investigation.
The Independent Police Complaints Commission said the computer claim no longer applied because it was a conduct issue covered by police regulations.
Local politicians said the claims had to be examined with transparency.
Carmarthen East and Dinefwr MP Adam Price said: "I held a meeting with Terrence Grange only a little over a week ago and was given no indication that he was on the verge of stepping down.
"The allegations against Mr Grange are concerning and must be investigated with the utmost transparency."
Llanelli AM Helen Mary Jones has asked Dyfed-Powys Police Authority to explain why he "has been allowed to retire in this way".
"There will be complaints that can no longer be investigated by the independent commission, particularly around the misuse of computers," said the Plaid Cymru AM.
"This apparent lack of transparency risks undermining the faith of our communities in their police force and that would be unfortunate."
She praised Mr Grange's policing, but said: "I think for his own sake he should have stayed in his post and answered the questions the independent commission wanted to ask".
TERRY GRANGE'S BIOGRAPHY
Terry Grange is married with three adult daughters
Joined the Army at 15, serving with the Parachute Brigade
Has a Masters degree in public services
Joined the Metropolitan Police in 1971
Joined Avon and Somerset Police in 1988, becoming assistant chief constable in 1994
Became Dyfed-Powys chief constable in 2000
The IPCC said it would examine if there was enough evidence in the financial irregularities allegation to submit a file to the Crown Prosecution Service.
The police authority announced on Monday that it had accepted "with regret" his retirement with immediate effect.
It said Mr Grange "had indicated that he had allowed his private life to interfere with his professional role".
There are reports that Mr Grange retired after asking the police authority to back him, and being refused.
"He went to ask for the support of the police authority but it was not offered. He had not wanted to retire," a police source, who did not want to be identified, told the Press Association.
Gary Mason, a former editor of the Police Review, said normally in this sort of case an officer could be fined or reduced in rank, but added: "Clearly, in this case this wouldn't apply because the individual involved is already retired on a full pension."
Mr Mason said there was not much the IPCC could do: "They can go through the motions and publish a report but unless it turns into a criminal investigation, that, I think, would be the end of the matter."
Acting deputy chief constable Andy Edwards said the force "would continue to maintain its high standards".
"The force has an enviable reputation for performance and enjoys a close relationship with its many communities throughout the force area," said Mr Edwards.
"None of that will be compromised as a result of Mr Grange's retirement, following his long and successful association with the force.
"He leaves the organisation with another outstanding year's figures in respect of all aspects of operational performance."
John Antoniazzi, a former chairman of Dyfed-Powys Police Authority, said he was greatly surprised.
"He led the force to a very high position in the 43 forces of England and Wales and we are very proud of that position, a position he held for some time."
Home Office minister Tony McNulty, at an Association of Chief Police Officers conference in Cardiff, said: "I would simply say that whatever the outcome of the IPCC report and whatever Terry has decided to do over his future, he has made a significant contribution to policing in Wales and for that he is to be congratulated."