Police hunting for thieves who stole a van carrying between 250 and 300 blood samples, have shut the case because of a lack of evidence.
The vehicle, which was also carrying urine samples, microbiology swabs, and smears, was stolen from outside a GP surgery in Morden near St Helier.
Officers were seeking a white man aged between 25 and 30 who they believe they took the van, but have now decided they will take the investigation no further.
A Merton police spokesperson said: "We have investigated the circumstances surrounding the theft of a motor vehicle.
"The matter was fully investigated, however, there was no CCTV, no forensic opportunities and no known suspects.
"Due to these factors, the investigation has been closed. If any new or further evidence comes to light it will be re-examined and investigated fully."
The van was parked outside the Faccini House Surgery in Middelton Road, near St Helier, when it was taken shortly after 2pm on Wednesday, July 30.
Merton police have confirmed the keys were left in the ignition when the vehicle was stolen.
Anyone who submitted a blood sample on Tuesday or Wednesday before the theft, at any one of nine south west London surgeries, or Croydon University Hospital, could be affected.
A full list of the GP surgeries which had their samples stolen can be seen at the bottom of this story.
Dr James Marsh, joint medical director at Epsom and St Helier Hospitals said: "I am sorry to announce that a vehicle used for collecting pathology samples from local GP surgeries for testing at St Helier Hospital was stolen.
"Although we are deeply disappointed that someone would choose to steal the van and its contents, our absolute concern at the moment is making sure any impact on patients is as minimal as possible."
An Espom and St Helier Hospital spokesperson said: "As you would expect in light of such a serious issue, we have launched an internal investigation which is ongoing.
"We are currently working with our GP partners to make sure that patients get their re-tests as soon as possible.
"Thanks to the speedy response of our GP colleagues many patients have already been contacted and their re-tests have already been completed."
The incident affects patients who had samples taken at the following practices:
Croydon University Hospital, haematology department
Brigstock Medical Practice, 141 Brigstock Road, Thornton Heath
Wide Way Medical Centre, Mitcham
The Rowans Surgery, Streatham
Tamworth House Medical Centre, Mitcham
Cricket Green Practice, Mitcham
Mitcham Medical Centre, Mitcham
Princes Road Surgery, Wimbledon
The Lambton Road Medical Practice, Raynes Park
The Grand Drive Surgery, Raynes Park
If you have any information about this incident, please contact Merton police on the non-emergency number 101.
Do you think the police should keep investigating? Are you a patient affected by this theft? Call the news desk on 0208 722 6358 or email firstname.lastname@example.org