Carried out by the Zito Trust - set up by Jayne Zito after her husband was killed by a man with schizophrenia - the survey showed these are not "rare tragic events".
More than half the killings were carried out by patients who had failed to take prescribed medication or failed to co-operate in their treatment. At least 40 per centhave been committed by people unknown to their victims.
So far nearly 40 cases have had reports completed although the findings have not always been published.
The 104 include cases such as that of Darren Carr, who killed the two children he minded and their mother.Anthony Smith, who killed his mother half brother; and Christopher Clunis, who killed Jonathan Zito, astranger, in a Tube station. "I feel very cynical about the response that has taken place since Jonathan's death," Mrs Zito told BBC's Panorama. "The professionals are not looking at the extent of problems faced by people being discharged into the community. I'm sick of hearing people say `these rare tragic events'."
The survey's findings mirror the Boyd report in 1994which found there had been 34 homicides in 18 months. The report denied the "common perception" that mentally ill people are likely to behave violently and says that in the context of 600 to 700 killings a year, homicide by psychiatrically ill people is "very rare indeed".
Under legislation passed after the Zito case, every released patient must have a "care keyworker". They must also have a plan for their care and a home to go to.
But there are fears that people are not always getting the care that they need. Dr Martin Deahl, a consultant psychiatrist at the Homerton Hospital, in east London, tells the programme: "There are people walking around who I think are potentially dangerous. Wen a serious offence is committed the hairs on the back of my neck stand on end because I just pray to God it's not one of mine."
Dr Deahl called for it to be made easier to section people and bring them into hospital and in some case to ensure that patients continue their medication after release to forcibly inject them.
"If we are going to let people out into the community ... there has to be some increased risk. We cannot eliminate this risk, all we can do is keep that risk to a minimum," he added.
Panorama; BBC1; 10pm tonight.
-Glenda CooperReuse content