Almost 30 years since 96 men, women and children were killed at the FA Cup semi-final between Liverpool and Nottingham Forest at Sheffield Wednesday’s Hillsborough football ground, the trial has started of the police officer in command of the match, David Duckenfield, on a criminal charge of gross negligence manslaughter.

Graham Mackrell, the Sheffield Wednesday club secretary and safety officer at the time of the disaster, is standing trial alongside Duckenfield, on two counts of breaching his duties under safety legislation.

Relatives of some of those who died at Hillsborough were at Preston crown court to see the trial begin with the process of selecting a jury of 12 people from 100 who filed into the courtroom.

The judge, Sir Peter Openshaw, told them jury service was “a necessary public duty which must be undertaken by ordinary citizens like yourselves”, then read 10 questions they must answer to determine whether they were likely to be suitable to reach “independent and impartial” verdicts.

The questions included whether they, or close relatives or friends, knew Duckenfield or Mackrell; were police officers; employees of any criminal justice agency; were employed by the Football Association, Sheffield Wednesday football club or Sheffield city council; were supporters of Liverpool, Everton, Sheffield Wednesday or Nottingham Forest; lived in or near Skelmersdale or Ormskirk – areas close to Liverpool that are within the Preston court’s jury service catchment area – or were students between 1984 and 2003 of Edge Hill University, where substantial academic work on the disaster was undertaken.

The questionnaire also asked people whether they or close family or friends had been at the match or were close to somebody killed or injured; or “whether there is anything that will prevent you from returning independent and impartial verdicts in these proceedings based only on the evidence you will hear”.

Openshaw told them that question was not “an easy way out” of jury service, but they must declare if they had “a settled opinion” about the Hillsborough case.

Duckenfield and Mackrell sat not in the dock but in the body of the court among their lawyers as the trial began.

Duckenfield, newly promoted to chief superintendent by South Yorkshire police when he took charge of the semi-final on 15 April 1989, is charged with failing in his duty to take reasonable care for the safety of spectators at the Leppings Lane and north stand areas of Hillsborough designated for 24,000 Liverpool supporters.

The indictment alleges that Duckenfield’s failure to protect the spectators from overcrowding and crushing amounted to gross negligence, and was “a substantial cause” of the deaths.

Mackrell is charged with failing to agree with the police the number of turnstiles for Liverpool supporters’ admission to the Leppings Lane terrace, and failing to take reasonable care under the Health and Safety at Work Act 1974, including by failing to draw up contingency plans for coping with a large build-up of spectators outside the ground.

Both men have already pleaded not guilty to the charges.

Duckenfield is charged with manslaughter in relation to only 95 of the people who died at Hillsborough. No charge could be brought in relation to the death of the 96th victim, Tony Bland, who was maintained on life support in hospital for four years until it was lawfully withdrawn in 1993. According to the law in 1989, a charge of manslaughter could not be applied if the victim died longer than a year and a day after the alleged criminal acts.

Richard Matthews QC, the lead barrister for the Crown Prosecution Service, will open the case once the jury has been selected.