Harold Shipman was planning an appeal against his conviction for 15 murders before he was found hanging in his cell, his solicitor said today.
Giovanni di Stefano expressed his surprise that Shipman, "who at last had a chance" to appeal, "suddenly commits suicide - a day before his birthday".
He told Sky News that he had been working on an appeal for Dr Shipman and had been awaiting the outcome of a retrial case at Chelmsford Crown Court, which succeeded.
"Based upon that precedent, there would be further grounds of appeal for Dr Shipman," added Mr di Stefano.
"Having succeeded in that case and having notified Dr Shipman and sent him a copy of the transcript that we had succeeded, it is extremely strange, to put it mildly, that a person who at last is given a chance, not much of one, of succeeding in getting an appeal off the ground would then suddenly kill himself."
He called for a "proper and full inquiry" and said the Prison Service should have learnt its lesson since Fred West committed suicide while awaiting trial.
He added: "For the alleged victims, this will not be seen as justice."
Shipman had been on suicide watch "for a short period of time".
But Mr di Stefano added: "Dr Shipman had never ever accepted his guilt and he's never ever admitted culpability in any of the murders that he's convicted of.
"Something is not really quite right there... No allegations from myself.
"A person who has a ground of appeal, a precedent in the Court of Appeal to allow themselves to appeal, suddenly commits suicide a day before his birthday?
"A person who is supposed to be the biggest mass murder in the United Kingdom, with so many deaths on his hands allegedly ... is left unattended in this way.
"We need to make inquiries as to whether anybody that had gone to his cell to see what was happening in the middle of the night. We just don't know."