People could have been wrongly convicted following allegations of "data manipulation" at a forensics lab in Manchester, a police chief constable has warned.
The head of the Dorset force, Debbie Simpson, said 484 cases were being reviewed after a criminal probe was launched into the matter.
Two men have been arrested by Greater Manchester Police (GMP) over allegations that hundreds of cases handled by Randox Testing Services were affected by what the National Police Chiefs' Council (NPCC) called "data manipulation".
Ms Simpson, who is the NPCC's lead for forensic science, told BBC Radio Four's Today programme that it was a "possibility" some people could have been wrongly convicted.
"Clearly, the integrity of both police processes, and the wider criminal justice system, is of great concern to us."
Asked if the cases being re-examined could include murder investigations, the chief constable said: "There may well be."
She added: "But in cases that are more serious it is very unusual that one single strand of evidence actually makes the case in its entirety, there is lots more evidence that is gathered."
Ms Simpson said that samples were being retested, stating: "If we find that it has been compromised we will ensure all the evidence is put together and reprovided to the Crown Prosecution Service."
GMP said that two men, aged 47 and 31, had been arrested on suspicion of perverting the course of justice and bailed until next month.