A sixth prisoner has died with suspected coronavirus in Scotland.
The Scottish Prison Service confirmed the death of HMP Perth inmate Alex Drysdale on Friday.
The 65-year-old was convicted at Kirkcaldy Sheriff Court in February.
It follows the death of another Perth prisoner, 68-year-old George Greenshields, on Thursday. Greenshields was convicted of murder at the High Court in Glasgow in 1988 after killing a homeless man, then burning his body.
He was given early release in 2005 but was recalled under the terms of his life sentence the following year after pleading guilty to slitting a man's throat.
Last month, the deaths of four prisoners were announced which were believed to be linked to the virus.
Sex offender Gordon Pinkerton, 75, was serving his sentence at HMP Dumfries, while John Dargacz, 54, was a prisoner at HMP Low Moss.
Serial sex offender John Angus, 66, held at HMP Edinburgh, was the first Scottish prisoner to die after contracting the virus.
After his death was announced on 10 April, murderer Francis McCarthy, 59, serving a life sentence at HMP Low Moss, became the second prisoner whose death was linked to Covid-19.
Separately, two more prisoners have died in custody this month.
William Price, 78, who as on remand at HMP Kilmarnock, is said to have died from natural causes.
James Connor, 55, an inmate at HMP Grampian, also died earlier in May. The SPS said his cause of death was being looked into.
The SPS said in a statement that Police Scotland has been informed of all the deaths and they will be reported to the procurator fiscal.
As is standard for deaths in custody, fatal accident inquiries will be held "in due course".
As of Thursday, there were 21 prisoners self-isolating in six locations across Scotland, of which two have tested positive for Covid-19.
A total of 143 prisoners have now been released early by the SPS as a response to the Covid-19 pandemic.
All were short-term prisoners, with less than three months of their sentence to be served.
It is expected a further 20 prisoners could be released over the weekend.
Scotland's prison population has decreased by more than 1,000 since the lockdown began and on Thursday was below 7,000 for the first time since 2008.
An SPS spokesman said: "This is partly because of the reduced numbers coming into prison from the courts, which are affected by lockdown measures, as well as the early release programme.
"The reduced prison population is making social isolation easier to achieve.
"But as numbers move up in the future, keeping prisoners separate could become more problematic."
The contagion is also having an impact on staffing in Scotland's prisons.
On 8 May, 560 staff, 12.6% of the total workforce, were absent from their work specifically due to reasons related COVID-19.
This included those who were symptomatic, self-isolating, shielding or caring for family members.
About 50 - 1.1% of the total workforce - were reporting to be symptomatic.
There were 823 members of staff absent across the SPS - 18.6% of the total workforce.
The SPS figures showed a further 263 staff were on sick leave, meaning 18.6% of the total workforce was unavailable.
The prison service has introduced a number of measures to help reduce the spread of Covid-19, including suspending all prison visits, education classes, communal dining and non-essential prison work.
It also restricted numbers attending exercise or recreation at any one time, closed prison gyms and increased the frequency of hygiene procedures.