[2] Most of what is known of Columba is due to two parishes in Cornwall that name her as their patron saint and a manuscript in the collection of the University Library of Cambridge, written by Cornish Roman Catholic activist and scholar Nicholas Roscarrock during the reign of Elizabeth I and based on local tradition.

An angel helped her escape and led her into the desert, where she was captured again by a local king, who admired her beauty and grace, and offered to marry her to his son if she renounced her faith.

An angel again helped her escape, and she fled to the coast and boarded a ship that took her to Cornwall at what is now Trevelgue Head (which is translated to English as "red dirt"; Cornish historian Nicholas Orme speculates that this refers to the color of the soil at the site of the martyrdom and the manner in which it took place).

[2] The king found her at Ruthvoes in central Cornwall, three km south of St Columb Major and 10.5km east of Newquay, and beheaded her.

They were written down in Cornish by the late 16th century by a physician who worked in St Columb Minor or a nearby town and were addressed to Roscarrock.

[4][6] Local tradition states that at the site of Columba's execution,  "a spring gushed forth along the path of her fallen blood",[3] and was marked in Roscarrock's day by a well; as of 2000 traces of the well and a cemetery remained there.