Talk of the man has come in documents and emails released to the Otago Daily Times under the Local Government Official Information and Meetings Act.
The documents show contractor Delta responding that none of its cemetery team was younger than 45.
But that suggestion has been questioned by Heritage Roses Otago convener Fran Rawling, who said it appeared Delta "brought people in" to do work who were younger.
Council recreation planning and facilities manager Jendi Paterson said there had been "a lot of speculation" in the early days of the matter, and plenty of theories.
"I’ve never been a detective, but you need some facts."
Those had not been forthcoming.
"In terms of investigation, it will remain a mystery, I think."
Last December, it emerged the roses had been sprayed with herbicide, and the council conducted soil and foliage tests. The chemical was identified as Picloram, used in brush killer products like Tordon and Metsulfuron.
Acting group parks and recreation manager Tom Dyer said in March the test results, and other evidence, meant the results of the investigation were "inconclusive".
He said it was not, however, likely to be Delta because of the nature of spray damage, the location of spraying and the contractor’s long-time experience managing the cemetery.
Mr Dyer said Picloram was not used by Delta at the cemetery.
Documents released included reference to "the alleged sighting of a male Delta worker" in his 20s spraying at the cemetery.
Mrs Rawling said in a November 28 document she was working in the cemetery in September when a "young chap approached" and asked if he should spray a particular rose.
"He was told definitely not to go near the rose. From memory, I thought he would be early 20s, slight build and dark hair."
Asked about the sighting in a November 29 email, Delta contracts manager Peter Walker told council parks operations manager Hamish Black gardeners and mower operators working at the cemetery were all over 45 years old, and another worker was in his 50s.
Remaining cemeteries staff not assigned to the Northern Cemetery were both in their 40s.
"No other worker has worked in the cemeteries this financial year.
"There have been conflicting accounts by different people in regard to this person who has supposedly sprayed in the cemetery."
However, the accounts had varied in their timing, and were not clear on what work was undertaken.
"That makes it more difficult to determine if this was in fact a Delta employee."
Mr Walker said he was "keen to get to the bottom of this one".
In a further email on December 21, he told Mr Black staff had between eight and 30 years’ experience.
In a January 21 email to agrichemical specialist Peter Thomson, Mr Black said a track from the cemetery to Butts Rd had signs of spray.
Mr Thomson questioned whether the perpetrator parked in Butts Rd and sprayed from that point to the cemetery.
A February 7 email from two Southern Heritage Trust volunteers to cemeteries officer Annette Hutton noted a young man "spraying intensively" at the cemetery.
Women employed to do the job sprayed carefully and were the only ones to do hand weeding, but "some of the men swung around quite wildly while spraying".
A February 10 letter from Delta environmental services general manager Richard King said his team was "very saddened" about the damage to the roses.
Delta had taken the matter seriously, investigated thoroughly and did not believe the damage was a result of its operations.
It had, however, reviewed its agrichemical procedures and "could not fully exclude the possibility of cross contamination when decanting agrichemicals".
Following the review, Delta had reduced the types and number of chemicals stored, tightened security and tightened mixing and application procedures.
Ms Paterson said this week the council was "now looking forward".
"We’ve got a much, much closer relationship with Heritage Roses Otago now.
"I think that’s really positive."
That organisation was doing good work to locate species that were damaged for replanting.
Mrs Rawling said people she saw working at the cemetery were "definitely younger" than 45.
Although she could not be certain they were from Delta, she believed they were employed by the company.
She said while many roses were lost, "some have come away, but a lot of them that have come away are very deformed".
"Picloram is still in the soil, very much so."
The organisation was planning planting in July, and more testing of the soil would be done by botanic garden staff.
