Kash Heed's triumphant return to cabinet on Tuesday afternoon was muted only hours later when the special prosecutor who cleared his name resigned.

Terrence Robertson quit out of concerns he could be accused of being in a conflict of interest, admitting his firm had contributed $1,000 to Heed's campaign shortly before last May's provincial election.

In his withdrawal letter, Robertson said the RCMP asked him several weeks before he cleared Heed whether he felt there was a conflict of interest.

He told them No.

But on Tuesday, Robertson indicated he was concerned about public perception.

"Given that charges were not approved against Kash Heed and upon further reflection, I have concluded that my continuing as special prosecutor on this matter may well provoke comment from the public and media as to whether I am sufficiently independent to act as special prosecutor in this matter," his letter said.

Heed was reinstated after resigning last month after news the RCMP was investigating inflammatory mail-outs sent during last May's election campaign.

On Monday, on Robertson's recommendation, charges were laid against three of Heed's former campaign workers.

Robertson said in his resignation letter he has "complete confidence" his decision was made objectively, but it would be inappropriate to continue.

"I do not wish this possible perception to impair the orderly progress of a prosecution on this matter."

Calls to Heed and Robertson weren't immediately returned.

Premier Gordon Campbell welcomed Heed back to cabinet Tuesday, noting Heed was exonerated by Robertson's investigation.

"Kash Heed has dedicated his career to public service and has acted in the best interest of his constituents," Campbell said in a news release Tuesday on Heed's reappointment.

"His commitment to the duties and responsibilities of solicitor general were paramount last month when he stepped aside. I am sure this has been difficult both for Kash Heed and his family."