Prosecutors in Northern Ireland are to consider the case against former British soldiers after detectives finished interviewing them about the killings in Derry on Bloody Sunday.
The deaths of 14 civilians during a civil rights march in Derry after paratroopers opened fire on 30 January 1972 are being re-investigated by police after a public inquiry found the victims were innocent.
Relatives of those killed want to see offenders prosecuted, a spokesman for the families said.
PSNI Detective Chief Inspector Ian Harrison said: "Police have concluded interviews with former military personnel and are in the process of compiling a report for the PPS (Public Prosecution Service).
"The families have been informed of this and we will continue to keep them updated in relation to developments."
Thirteen people were killed by members of the Parachute Regiment on the day of the incident in Derry's Bogside. Another victim died in hospital four months later.
Northern Ireland police launched a murder investigation in 2012.
It was initiated after a government-commissioned inquiry, undertaken by Lord Saville, found none of the victims was posing a threat to soldiers when they were shot.
Following the publication of the Saville report in 2010, then prime minister David Cameron apologised for the army's actions, calling them "unjustified and unjustifiable".
A petition calling for soldiers involved in Bloody Sunday to be granted immunity from prosecution has gained tens of thousands of supporters.
Three leading judges at London's High Court blocked the arrest and transfer to Northern Ireland of former paratroopers who faced questioning over whether they committed criminal offences.
The judges said there was no reason why the seven ex-soldiers could not be interviewed in England and Wales, where they live.
Stormont Assembly member and civil rights campaigner Eamonn McCann said effectively all the families supported prosecutions and welcomed the conclusion of the police interviews.