Cuts to funding for forensic science work are eating into essential services - heightening the risk of miscarriages of justice, an official watchdog has warned.
Gillian Tully flagged up the potential for wrongful convictions or evidence being missed as she raised the alarm over ongoing financial reductions.
Dr Tully, the Forensics Science Regulator, said: "A year ago I warned that funding was too tight, and now even more money has been taken out of the system. We cannot continue on this path."
She detailed how scientists have been required to give expert advice based on interim forensic reports because some police forces have refused to pay for them to produce statements of evidence that can be admitted in court.
Downward pressure on costs, which affects both commercial and government-funded organisations, has eroded the time available for professional development, the regulator said.
Publishing her annual report covering the year to November 2017, Dr Tully told the Press Association: "My concern is there was no fat in the system as it was.
"The more pressure you put on people, the less time they have to spend on their actual work, the more you raise the risk of errors.
"The worst case is that there are miscarriages of justice, either through the wrong person being convicted or through justice being denied to somebody because, for example, the evidence wasn't found when it should have been."
She called for the Government to put her role on a statutory footing so she can ensure all bodies providing forensic science evidence in the criminal justice system meet the required high standards.
Techniques including analysis of DNA, fingerprints and digital evidence play a major role in a range of criminal investigations.
The publicly-owned Forensic Science Service, which previously provided police with the majority of such work, was controversially closed in 2012.
Dr Tully warned some forces have missed the deadlines to achieve standards in their own forensic science practices, leading to a lack of independent assurance on the quality of the work.
She said: "Whilst it is understandable that senior police leaders have a wide range of priorities, if quality of forensic science provision is of insufficient priority to enable risks to be managed effectively and quality standards to be achieved, the logical result is that it will become unsustainable for any forensic services to be managed within some police forces."
Her report noted that progress has been made in the sector, with many organisations either meeting required quality standards or "well on their way" to doing so.
A Home Office spokeswoman said: "It is for Chief Constables and Police and Crime Commissioners to decide how best to deploy resources to effectively manage crime and local priorities, including forensic services.
"However, we are clear that cost savings must not come at the expense of a reduction in quality standards."
She added that the Government is committed to putting the regulator on a statutory footing "at the earliest opportunity".
National Police Chiefs' Council lead for forensics Debbie Simpson said: "As with much of policing, Chief Constables are being forced to make difficult decisions about how they utilise their limited resources, but we remain completely committed to meeting the requirements of accreditation and further improving confidence in the criminal justice system.
"Forces continue to develop in-house solutions and work with the private sector to deliver the highest possible quality of forensic services, and while some have not yet met the deadline for accreditation I am confident that they are fully committed to doing so."