Vulnerable mental health patients regularly go missing from hospital an investigation has discovered, with some not recovered for more than two weeks.
Figures obtained by the Wandsworth Guardian show more than 80 patients went missing from Springfield University Hospital in the past four years, compared with just three in 2009.
The investigation was prompted by the disappearance of patient Mark Ricketts, convicted of stabbing a stranger 20 times in 1994, for four days before the public were warned in March.
He was found on a bus in Lewisham by police, after media put out warnings.
Responding to the figures, director of nursing, Andrew Dean, said he could not account for the rise, which peaked in 2011 with 28 absconders.
He did emphasis many cases of patients being recorded missing is not due to an escape, but because they failed to report back to staff after periods of unescorted leave, organised as part of their rehabilitation.
The longest period a vulnerable patient went off the radar was 20 days while 14 people were missing for over a week.
Mr Dean, said: "If I had a member of family in the hospital who went missing, I would feel how most families feel.
"I would be really worried about it.
"But because I work here, I know the rigorous planning we do for people who go on unescorted leave.
"Part of our job is to reintegrate people back into society. First they go on escorted leave, then further down the line they can go out on their own.
"However, we are dealing with human beings. They sometimes do things we don’t expect, and sometimes they don’t stick to the promises they have made."
Before a patient is allowed on leave, a review is carried out to assess how likely they are to abscond.
It is hoped a new ‘multi-disciplinary procedure’ will reduce unauthorised absences.
He said: "A patient will be dealt with by a range of different staff members.
"We are now joining the dots. We wouldn’t have made a decision with the help of so much information before."
The hospital is divided into three acute wards, four forensic wards and departments for conditions such as obsessive compulsive disorder and eating disorders.
Patients in the acute ward either check themselves into the hospital, or are referred by a mental health trust.
The forensic ward is for people considered dangerous to others, or who have a criminal conviction.
The hospital is building a 5.2 metre fence around the forensic ward, but there are no plans to secure the grounds in another way.
Springfield Hospital said no one has left a ward with a secured perimeter since 2011, when they started recording such instances.
David Bradley chief exec of South West London and St George's Mental Health NHS Trust
Following the disappearance of Mr Ricketts, Tooting MP Sadiq Khan raised concerns about the blunder in a letter to the hospital’s CEO David Bradley.
Mr Bradley wrote back to the MP on April 3, stating he was on unsupervised leave and failed to return.
Mark Kemp, the victim of the Mr Ricketts' attack 20 years ago, said: "The place should no longer be able to take patients with criminal convictions.
"I didn’t even know he was missing, there could have been seeds of revenge and he could have come looking for me or my family.
"There’s no accountability in the hospital, when this sort of thing goes wrong there’s no one person you can complain to."
Victim: Mark Kemp