Patricia Ann Kucerovsky, a teacher and mother of two, died of mercury poisoning in 2008. (CBC)

No charges will be laid in the 2008 mercury poisoning death of Patricia Ann Kucerovsky, according to the Fredericton Police Force.

The homicide investigation has been deemed "inactive until sufficient information is available to support continuing the investigation," Const. Danielle Carmichael stated in a release on Tuesday.

"As the case currently stands, police do not have sufficient evidence to lay a charge," she said.

Kucerovsky, 43, of the Beechwood Crescent area, died at the Dr. Everett Chalmers Hospital on Aug. 19, 2008, after a short period of illness.

Her death was quickly deemed suspicious and a "very complex" investigation ensued, said Carmichael.

A 44-year-old male suspect was arrested in November 2011, but later released unconditionally. One month later, investigators deemed Kucerovsky's death a homicide.

Last summer, police issued a plea to the public for information and received "several calls," but investigators followed up on them to no avail, said Carmichael.

"As we have stated on many occasions, this is a very intricate, highly unorthodox case and has been so from the onset," she said.

"The investigation surrounds mercury poisoning which is not something the Fredericton Police Force, nor most law enforcement agencies in Canada have dealt with."

Kucerovsky, a teacher and mother of two, had "very significant levels of mercury in her system," police have said.

Mercury poisoning damages the central nervous system and the kidneys, and in heavy exposure it can cause brain damage and ultimately death.