When Roger Avary, the Oscar-winning screenwriter of Pulp Fiction, was last month sentenced to a year behind bars for his role in a fatal car crash, it seemed that a promising writing career had come to an abrupt end.

But a string of posts on social networking site Twitter has revealed that he is apparently still chronicling the underbelly of American culture.

In a series of 140-character takes, Avary has built up a vivid portrait of life in Ventura county jail where he is currently being held. "Sickness spreads throughout the facility like brush fires," he writes in his latest tweet from November 22, "and #34 [his identification number in prison] is helpless to avoid the outbreak and inevitable infection."

Though there has been no official confirmation that the Twitter feed is Avary's, there are various clues to its authenticity, including the fact that his professional website avary.com links to it.

The film-maker was sentenced in September to a year in jail and five years probation after he pleaded guilty to manslaughter for his role in a fatal crash in January. Prosecutors said he had driven while drunk at speeds over 100mph, eventually hitting a telephone pole.

Andreas Zini, 34, who was visiting California on his honeymoon, was killed, and Avary's wife was seriously injured.

The crash appeared to have put an end to Avary's Hollywood career. In 1995 he won an Oscar with Tarantino for the script they wrote for Pulp Fiction. He also directed Killing Zoe and The Rules of Attraction, and co-wrote and produced Robert Zemeckis's Beowulf (2007).

His time inside has been hard, judging from his tweets. He admits to having been "so afraid" at the start, and intimidated by the guards. "Nightly, every few hours like clockwork, a guard's flashlight beam strikes #34's face, perhaps to ensure lack of proper rest and exhaustion."

The "clean" sheets reek of the sweat of a thousand men, breakfast porridge is made with oats from sacks with a picture of a horse on them labeled "Not intended for human consumption", the windows let in little light and he is subjected to random strip-down and cavity searches by a "leering, rotund officer".

On the upside, there is the kindness of his cellmates, occasional books to read and lessons from other inmates in how to slimjim and hotwire a car.

Night is the worst. "Night falls, and the only real activity is an endless recounting of the terrible and pointless events that brought us all to this sad place."

The puzzle is how Avary is managing to update his Twitter feed from jail. The Los Angeles Times points out that most of the entries are through a Web browser, suggesting he may have regular computer access, while others are through Twitterific, an iPhone app.

Another theory is that he is reading out his 140 characters down the phone to a friend, who is updating Twitter for him.