Corrections said it received an alert, but that was among thousands of alerts it received that day from people being electronically monitored across New Zealand.
The daylight stabbing at New Windsor Dairy early last month left its owner Suresh Patel critically injured.
Patel has only just reopened his shop in the past few days and is still recovering from the cuts to his face and neck. He struggles with chewing, and is dealing with swollen stitches and an eye injury.
Suresh Patel said he is grateful that they survived.
“Our community, our friends [and] family, they prayed for us and God gave me the second life…because at that time I was thinking I am finished today, but lucky my wife is so brave, she tried to save my life.”
It said in a statement it received 3038 alerts that day for the 6000 people being electronically monitored - including no communication alerts - and it needed to prioritise the higher risk alert types.
“In a small number of cases, ‘no communication’ alerts can represent a person interfering with their tracker in an attempt to circumvent their monitoring,
“We are able to retrospectively identify when people are interfering with their tracker in an attempt to circumvent their monitoring, and when we identify someone acting in this way, we prioritise any ‘no communication’ alerts received relating to them,
“However, as this person had never been suspected of interfering with their tracker previously, the ‘no communication’ alert was not treated as likely interference and prioritised on this occasion.”
Corrections said when it looked at Lam’s tracker data after the assault, it found it was likely he was interfering was his tracker.
Victim advocate Ruth Money said the stabbing was preventable and it is concerning that Corrections is failing to monitor people on electronically monitored bail.
“For them to use an excuse of how many alerts they got in a day - that’s their job - it’s like saying you’ve received too many phone calls in a day… it’s your job to receive those alerts and monitor those risky offenders… and keep us safe, and they have failed woefully.
“I think it’s stretched to call it a monitoring service right now, we know people are putting foil, we know people are going out of service with low battery and nothing is happening, well certainly nothing is happening to the offender but plenty is happening within the community.”
Money said Corrections must be open about what changes will happen immediately to ensure the community is safe.
The dairy attack is not the only time where a person has offended while being electronically monitored.
It said it is also been actively recruiting and retaining electronic monitoring staff, halving attrition rate by about 50 per cent over the past year.
Corrections expects to report about its review into electronic monitoring to the national commissioner by the end of the year.
There are currently 1700 people on EM bail across New Zealand, compared to 495 as of June 2017.
Corrections’ national commissioner Leigh Marsh earlier told RNZ that the tamper and abscond rate of electronic bail bracelets rate sits at around 1.4 per cent for July this year.