Kristi Noem, the South Dakota governor and Republican vice-presidential hopeful, may have committed a class two misdemeanor offence when her fated dog Cricket, a 14-month-old wirehair pointer Noem deemed “untrainable” for hunting pheasant, killed a neighbor’s chickens.

Under South Dakota law, “any person owning, keeping, or harboring a dog that chases, worries, injures, or kills any poultry or domestic animal is guilty of a class two misdemeanor and is liable for damages to the owner thereof for any injury caused by the dog to any such poultry or animal.”

Though Cricket’s chicken attack has made headlines in recent days, however, it was not the main subject of such reports.

Instead, Noem’s startling description of her decision to kill Cricket – and also an unnamed, un-castrated and unruly goat – has pitched her into an unprecedented political storm.

The story is included in Noem’s new book, No Going Back: The Truth on What’s Wrong With Politics and How We Move America Forward.

The book will be released next month. Last week, the Guardian obtained a copy and reported the passage in which Noem describes killing Cricket and the goat after Cricket first ruined a pheasant hunt, then killed the chickens.

“I hated that dog,” Noem writes, before describing how she shot Cricket and the goat in the same gravel pit, the goat having to be shot twice, the second shotgun blast after Noem left the goat to fetch more shells from her truck.

Noem says what she thought she had to do was not “pleasant”, and describes how her actions startled a construction crew and confused her young daughter.

She also seems to acknowledge the possible effects of including the story in her book, writing: “I guess if I were a better politician I wouldn’t tell the story here.”

News of Noem’s tale did indeed set off a political firestorm, with observers suggesting she had irrevocably damaged her chances of being named running mate to Donald Trump, the presumptive Republican nominee for president who faces 88 felony charges of his own and was adjudicated a rapist but nonetheless maintains his grip on his party.

Noem twice defended her account of killing Cricket and the goat, saying as she does in the book that such actions are sometimes necessary in farming, and show her willingness to do difficult things in life as well as in politics.

But each defense added to her problems.

In the first statement, Noem both referred to recently putting down three horses and advertised her book, promising “more real, honest and politically incorrect stories that’ll have the media gasping”. That drew accusations of insensitivity.

In her second statement, Noem said she could “understand why some people are upset about a 20-year-old story of Cricket” but added: “The fact is, South Dakota law states that dogs who attack and kill livestock can be put down.

“Given that Cricket had shown aggressive behavior toward people by biting them” – Noem says the dog “whipped around to bite me” after killing the chickens – “I decided what I did.”

In a separate section of South Dakota’s codified laws, the definition of livestock makes no mention of poultry, which would have meant the law did not apply to Noem.

But asked about a South Dakota legislature definition that says livestock “means cattle, sheep, horses, mules, swine, goats, and buffalo”, omitting chickens or poultry in general, Ian Fury, Noem’s communications chief, advised the Guardian to “take a look at SDCL 40-34-1 and 40-34-2.”

When the Guardian did, questions arose.

Section 40-34-1 of the South Dakota codified laws – Killing of dog lawful when disturbing domestic animals – says: “It shall be lawful for any person to kill any dog found chasing, worrying, injuring, or killing poultry or domestic animals except on the premises of the owners of said dog or dogs.”

Noem writes that she killed Cricket on her own property.

The following section – 40-34-2, Liability of owner for damages by dog disturbing domestic animals – seems to contain greater potential legal jeopardy.

It says: “Any person owning, keeping, or harboring a dog that chases, worries, injures, or kills any poultry or domestic animal is guilty of a class two misdemeanor and is liable for damages to the owner thereof.”

In her book, Noem writes that she apologised to the family that owned the chickens Cricket killed, “wrote them a check for the price they asked, and helped them dispose of the carcasses littering the scene of the crime”.

Asked if SDCL 40-34-2 indicated that Noem might have committed a class two misdemeanor, Fury did not immediately comment.

The South Dakota laws apparently applicable to the case of Noem and Cricket were passed before the dog’s death.

In her weekend statement, Noem said her story was 20 years old. That would place it in 2004, when she was in her early 30s, three years before she entered South Dakota state politics and six years before she won a seat in Congress as part of the hard-right Tea Party wave. Noem was elected governor of South Dakota in 2018.

South Dakota was the last of the 50 states to make animal cruelty a felony, passing legislation in 2014.