West Yorkshire Police Assistant Chief Constable Tim Kingsman described it as "clearly regrettable" that Hartley had been allowed to keep his liberty for so long.
A judge blasted police and magistrates who granted a serial rapist bail on SIX occasions before he went on to attack a woman in her own home in front of her child.
In a statement issued this afternoon, Mr Kingsman said: "Carl Hartley is a highly dangerous sexual predator who was investigated on multiple occasions by police between 2014 and 2016 in connection with the four offences he was eventually charged with.
"It is clearly regrettable that he was on the streets for so long and we wish to express our sympathy to the victims.
"We note the judge’s comments in relation to this case, including those regarding the hard work of the officers who brought Hartley to justice."
A timeline of rapes and attacks carried out by Hartley - and the times he was bailed
February Hartley rapes first victim in street after following her from Wakefield city centre pub.
May - Second victim raped in alleyway behind Wakefield Prison after being followed from nightclub.
- Hartley arrested days later. Given bail after denying attack.
- Hartley linked to first offence. Denies rape and bailed.
June - Hartley arrested on suspicion of another rape offence. Bailed after denying it.
July - Arrested for a fourth time on suspicion of yet another rape. Bailed.
June - Detectives put together "package" identifying Hartley as a serial rapist, which is presented to the Crown Prosecution Service.
- Hartley charged with four offences of rape but bailed.
- Hartley breaches bail conditions and brought before magistrates in Leeds. He is given bail YET again.
- Hartley sexually assaults woman in her own home in Leeds in front of her three-year-old child.
- Finally arrested and remanded into custody
- Hartley given life sentence after pleading guilty to two offences of rape and one of sexual assault