Ba as  Oxelösund, sa tSualainn, do Nils-Olof Franzén. Bhí sé an-tugtha don úrscéal bleachtaireachta. Ina Cheannasaí ar Raidió na Sualainne a bhí sé ón mbliain 1956 go dtí an bhliain 1973. Caitheamh aimsire aige ba ea scéalta bleachtaireachta don aos óg a chumadh. Bleachtaire nach bhfuil aon easpa féinmhuiníne ag baint leis is ea Agatán Sacs.

Faoi cheilt san ainm sin, Agatán, tá Agatha, ar ndóigh, mar bhí an-mheas ag an Sualannach ar leabhair Agatha Christie. Bhí broc-chú ag muintir Franzén darbh ainm Ticí agus faightear sna leabhair é mar pheata an bhleachtaire féin. Chomh maith leis sin, bhí scata aintíní fuinniúla údarásacha ag muintir Franzén agus faighimid duine acu sna leabhair bhleachtaireachta i bpearsa Aint Máire Treasa atá go maith in ann an fód a sheasamh.

 Nuair a thugadh sé an broc-chú amach ag siúl, is ansin a chíoradh sé plotaí na leabhar bleachtaireachta ina aigne. Ba nós leis éirí go luath sula mbeadh an chuid eile acu ina suí agus luí isteach ar na heachtraí. Chloiseadh an chlann é agus é ag gáire dó féin faoi na nithe áiféiseacha a bhí ag titim amach ar an leathanach os a chomhair.

Chum sé scata úrscéalta staire agus ábhar eile don aos óg. Chuir sé spéis i gceol agus i dteangacha. Fear mór rothaíochta ba ea é. Thaitin sé leis ceoldrámaí puipéadóireachta a léiriú don teaghlach, go háirithe ceoldrámaí de chuid Mozart. Bhí áit speisialta ina chroí ag an 11 leabhar Agatán Sacs, leabhair a thaitneodh go mór le glúin i ndiaidh glúine de léitheoirí óga ag baile agus i gcéin.

Nils-Olof Franzén, from Oxelösund in Sweden, was a fan of detective mystery novel. He worked as the boss of Swedish radio from 1956 to 1973, and as a hobby wrote his own detective novels for young people, creating the supremely confident and entertaining sleuth, Agatán Sacs (whom he named after his favourite crime novelist, Agatha Christie). The Franzén family had a little dachshund called Ticí, who found her way into the Agaton Sax books as the detective’s own dog. They also had many energetic but stern aunties, one of whom inspired Aunt Máire Treasa in the stories. Both Ticí and Aunt Máire Treasa play a leading role in helping Agatán Sacs crack his cases and catch the criminals in these inspired adventures.

Nils-Olof Franzén would often work out the plots for the Agatán Sacs stories when he took Ticí for a walk. He would get up early in the morning, and begin writing his stories before the rest of the family was up — his children would often hear him laughing to himself as he created more ingenious and incredible situations for Agatán Sacs.

Nils-Olof wrote lots of historical novels and other literature for children, and was also interested in music and languages. He loved riding his bike, and put on puppet shows of operas by Mozart for his family. But he was especially proud of the 11 Agatán Sacs books he wrote, and how his stories were enjoyed in numerous countries and by several generations.