The Stormont-commissioned group has also recommended the setting up of a non-statutory independent panel that would run in parallel to the inquiry and allow the women and girls who were sent to the institutions to give testimony in a less adversarial format than an inquiry hearing.
The experts have also said that redress payments should be paid to survivors at the outset of the twin-track process.
Legislation should also be passed to ensure access to the records of the institutions under scrutiny, the panel urged.
Earlier this year a major academic research report was published outlining the scale of mistreatment endured by thousands of women and girls.
The work by Queen’s University and Ulster University found that more than 14,000 girls and women went through the doors of mother and baby homes, Magdalene laundries and other institutions between 1922 and 1990.
It found that women were mistreated, held against their will and forced to give up children for adoption.
The findings prompted Stormont ministers to commit to a full investigation of what happened in the institutions.
The Stormont Executive commissioned an expert panel to work with survivors to design the format of the investigation.
Outlining the findings on Tuesday, the chair of the Truth Recovery Design Panel, Deirdre Mahon, said: “For six months we have worked closely with victims-survivors and relatives who have shared their heart-breaking stories with us and we thank them for their dedicated and tireless pursuit of truth and justice.
“The Executive’s decision in January, on the Inter-Departmental Working Group’s advice, to decide to set up an investigation and involve victims and survivors centrally in designing the investigation was a hugely positive step. Nevertheless this decision has come too late for many, and it is essential that these recommendations are acted on without delay.”
Other measures recommended by the panel include the offering of public apologies from the State and all institutions involved; comprehensive funding for health and wellbeing services for survivors; funding for voluntary DNA testing; legal aid to access the courts or inquest system; citizenship for those who lost their entitlement due to removal from the jurisdiction as a child; and the provision of gravestones and memorials.
The academic research published at the start of the year found that more than 10,500 women and girls entered the homes for unmarried mothers and their children over a 68-year period from 1922.
The youngest was 12, and the oldest 44. However, a third were under the age of 19.
They included victims of rape, incest or unlawful carnal knowledge.
Girls and women were sent to the homes by their families or church leaders under a shadow of stigma, secrecy and shame, believing they had no other choice due to being pregnant out of wedlock.
Survivors of the institutions claimed they were subjected to labour such as scrubbing floors during the final stages of pregnancy and were described as “fallen” and stigmatised.
Meanwhile, 3,000 women were sent to Magdalene laundries with numbers peaking in the 1930s.
Some were referred to the austere institutions by their families, others by priests and some by state agencies, including the courts, police, probation, welfare and GPs.
These included women who suffered with alcohol dependency, teenage girls described as having behaviour issues, some with learning difficulties, and some from the mother and baby homes to serve “penance”.
Some women died in the laundries after spending the majority of their lives doing unpaid, strenuous labour.
A further 707 women entered an industrial institution run by the Salvation Army at Thorndale in Belfast which was described as being used as an alternative to prison, like a probation home.
Around 4% of babies were either stillborn or died shortly after birth across the entire period.
Around a third of infants were then sent to baby homes following separation from their birth mother. Others were fostered in today’s terms and others were placed for adoption.
Other expert members of the design panel who sat alongside Ms Mahon were Dr Maeve O’Rourke, a lecturer in human rights at National University of Ireland Galway, and Professor Phil Scraton, a Queen’s University academic known for his work investigating the 1989 Hillsborough disaster.