Ministry of Justice figures show 130 inquests into deaths were being dealt with by Nottinghamshire coroner's service at the end of 2020.
Of those, 23 had been open for over a year – including eight open for at least two years, an increase from the 18 open a year or more in 2019.
Inquests are held to investigate sudden, unnatural or violent deaths, those which are from unknown causes and those occurring where there is a legal requirement to conduct an investigation – such as in prison custody or while someone is sectioned under the Mental Health Act.
They should be completed within six months of a coroner being made aware of a death, or as soon as practically possible after that.
Cases involving complex legal or medical issues, or deaths abroad, can cause lengthy waits and coroners must report investigations lasting more than a year to the Lord Chancellor.
The Law Society said existing delays within the criminal court system, exacerbated by the coronavirus pandemic, also impact coroner services, with inquests adjourned where they are linked to on-going investigations, prosecutions or active Crown Court cases.
President Stephanie Boyce said waiting times across England and Wales at the end of 2020 – with more than 3,250 inquests open for more than a year waiting to be processed – reflect a ‘general lack of investment in the justice system’.
It took an average of 24 weeks for Nottinghamshire coroner's service to process an inquest last year, less than the national average of 27 weeks and representing an increased processing time compared to 21 weeks in 2019.
The average time varied last year between nine weeks for Black Country coroner's service and 50 weeks in North Lincolnshire and Grimsby.
Inquest director Deborah Coles said the figures highlighted a postcode lottery across coroner services.
She said long delays impact on the ability to grieve, adding: "As well as having a significant public function, inquests provide important answers for bereaved families.
"They are often the first opportunity they have to hear the truth about how their loved one died."
A House of Commons Justice Committee report on coroner services, published in May, also said pandemic restrictions caused considerable delays last year, as services had to account for social distancing, some struggling to accommodate juries as a result.
The report recommended central government funding support to help the coroner service recover from the pandemic and called for a unified national coroner service to address the "unacceptable variation" in standards between coroner areas.
A MoJ spokesperson said the pandemic had posed significant challenges but praised coroners and their staff for continuing to deliver vital services.
The Government provided local authorities with £4.6 billion to help them through the pandemic and wrote to councils to remind them of their responsibilities in ensuring coroner services remain operational, the MoJ said.
The department also highlighted a £110 million investment aimed at boosting recovery within the court system and said the number of outstanding criminal court cases had fallen since summer 2020.