The case of a teenager jailed for life after stabbing a lawyer to death has raised fresh alarm about the practice of releasing violent suspects without strict bail conditions.

Ewan Ireland was 17 when he attacked Peter Duncan in August. The sentencing judge said on Tuesday that it was the 52-year-old’s bad luck to accidentally bump into Ireland while trying to get home after work in Newcastle city centre.

At the time Ireland was “released under investigation (RUI)” for an offence of affray, was being investigated for a robbery, and subject to a 12-month conditional discharge for a battery offence the previous summer.

RUI is increasingly being used rather than imposing strict bail controls on suspects before trial. Tens of thousands of suspects including many accused of violent crimes are being released by police without bail restrictions, leaving victims and the public increasingly at risk, the Law Society has warned.

The practice became legal in 2017 – resulting in suspects, victims and witnesses waiting months and even years for justice.

James Mulholland QC, vice chair of the Criminal Bar Association, said: “We know of numerous cases where defendants are being prosecuted for serious offences allegedly carried out when that individual has earlier been RUI for other matters of gravity ranging from alleged rape or grooming of minors to weapons possession or even terrorism-related crime.

“This cannot continue. RUI invites prolonged delay and leaves victims of crime in a nightmare of uncertainty and fear from potentially extremely dangerous individuals whilst those who are innocent struggle to move on with their lives, constantly looking over their shoulders.

“RUI must go and the police must be given far greater resources to investigate cases swiftly and diligently in order for a decision to be taken as to whether there is sufficient evidence to charge or, at least, control exerted under the provisions of the Bail Act if further investigation is essential.”

Duncan’s family expressed their anger in court that the violent and dangerous teenage offender was out on the streets and free to kill.

Duncan, the father of two boys, and his killer accidentally brushed against each other at a busy entrance to the Eldon Square shopping centre, and Ireland reacted angrily and stabbed his victim in the heart with a screwdriver he had shoplifted minutes before.

Newcastle crown court heard Duncan struggled on for a few steps before collapsing near a Greggs outlet, and he could not be saved.

Ireland admitted murder at a previous hearing. Mr Justice Lavender sentenced him to life with a minimum of 15 years in jail, saying the term would have been longer if it had happened after he turned 18 in October.

The court heard Ireland has appeared in court on 17 occasions and has 31 criminal offences on his record. Psychiatric assessments deemed him a “dangerous offender”, said Richard Wright QC, prosecuting.

In a victim impact statement, Duncan’s widow, Maria, said: “The person who did this had convictions. Nothing stopped him. He continued and he murdered my husband.

“Please do not allow him to devastate any more families. He is a danger to all of us.”

Duncan’s 15-year-old son was in the city centre that evening for a cinema trip and saw the cordoned-off area without realising his father had been attacked.

In a victim statement, he said: “At the time [Ireland] had been released under investigation in relation to another incident in which a weapon was used. I am angry he was out free, and cannot understand why he was not locked up. If he had been we would still have my dad to this day.”

Caroline Goodwin QC, defending, said Ireland “had spoken of his absolute remorse and devastation at the act he occasioned which was needless and senseless”.

Sentencing, Lavender said Ireland’s offending started at the age of 14, and he has offences of theft, battery, public order and making threats with knives on his record.

A defence psychiatrist reported that Ireland had “severe autism spectrum disorder and intermittent explosive disorder” – the latter meaning he was unable to control “impulsive or anger-based aggressive outbursts”, the judge said.

The prosecution psychiatrist said he had “traits of autism spectrum disorder” and “conduct disorder” – symptoms of which include “excessive levels of fighting”.

The judge said: “On either view, you are clearly someone who finds it difficult to control your temper and to refrain from violence.”