South Australia's top cop says he's exasperated by slack court penalties which allowed a violent criminal to go free and on a rampage before killing himself.

Shane Andrew Robinson, 32, was found dead by police at a remote SA homestead on Thursday after stabbing a policeman, stealing his car, running over a stockman and sexually assaulting an elderly woman hostage.

Robinson had a lengthy criminal record dating back more than a decade, including the rape of a 12-year-old girl.

A warrant was issued for Robinson's arrest last month for breaching parole conditions. Police were looking for him to execute the warrant.

Robinson was involved in a siege last year and another in Adelaide in 2002 that ended when he was shot in the neck by police.

He'd been jailed for just over seven years in 2004 for "numerous offences", the SA Parole Board said on Friday.

He was granted parole in December 2007 but had since been returned to custody for brief periods for breaching parole conditions.

Last month, Robinson was found to have again breached parole.

The parole board's secretary, Kevin Hill, said a warrant for Robinson's arrest had been authorised on June 23. He was unable to say why it wasn't executed.

SA Police Commissioner Mal Hyde warned more violent crimes were inevitable unless court sentences were harsher.

"What occurred and the history of this person, is not an isolated incident," Mr Hyde told reporters on Friday.

"Frequently, we see serious offenders breaching parole and quite often we get exasperated by fairly lenient sentencing which, in our view, doesn't really protect the community.

"Robinson had a prior conviction for raping a 12-year-old girl - it's quite frustrating."

Mr Hyde said prison "probably" doesn't rehabilitate repeat offenders such as Robinson.

"The correctional system is a way of taking them out of circulation," he said.

Court records show Robinson had convictions dating back more than a decade for crimes including unlawful sexual intercourse, unlawful wounding and trespass.

SA Liberal leader Isobel Redmond called for a review of the monitoring of parolees to determine if there was any "systematic failure" that permitted Thursday's mayhem.

Robinson stabbed a policeman in the shoulder and stole his patrol car on the Barrier Highway near Yunta about 6.55am (CST) on Thursday.

He then ran over a 25-year-old pedestrian before breaking into the Bulyninnie Station, near Yunta, where he tied up an elderly woman and sexually assaulted her.

Robinson also forced the woman to open a gun safe where 16 firearms were kept.

Police entered the homestead and found Robinson dead more than 12 hours after he stabbed the officer and almost eight hours after the elderly woman escaped and told officers she thought Robinson had shot himself.