You learned to note who was loitering outside your hotel, to memorize faces in a train carriage, to scan a street while pretending to tie a shoe. Sometimes the agents stood out. During my first trip to Tunis in January 2009, I visited the ruins of Carthage. Three men I recognized from the train sat on a bench, hunched in their coats, watching me explore the stumps of columns.

I returned nine months later to cover presidential elections. Campaign posters of Ben Ali -- hand on heart, a serene smile under black brilliantined hair -- were multiplying on the walls.

One afternoon I realized that only a single agent was following me.

"I can ditch this bastard," I thought, and darted into the old city. The alleys were thick with shoppers browsing among the scarves, carpets, lacquered serving dishes, embroidered gowns, and other flashy bric-a-brac.

I zigged, I zagged, I doubled back, and he zigged, zagged and doubled back with me. We were moving uphill and I could see him breathing heavily. I stepped around a corner. After a moment he trudged into view.

"Peace be upon you!"

He froze. For a moment he looked at me mutely. Then the words slipped out: "And upon you be peace."

"Look, you and I are going to be together all day, so I'd like to introduce myself," I said. I was excited and speaking quickly. "My name's John."

He eyed me warily.

"And you?" I said.

Another pause. Then he told me his name. He didn't know who I was or what I was doing, he said. Only that he must follow me.

"You understand why sometimes I try to run away?" I said.

No answer.

"Anyway I'm having a coffee," I said. We were beside a café. "Can I get you one?"

No, he said, but thanked me. He waited while I drank my coffee, and later waited outside a mosque while I tried to interview worshippers. When I came out he waved me over. He had his cell phone in hand and clicked through photos to a baby gathered in blankets.

"My son," he said, and smiled. "My first."

He followed me the next day, and after that I didn't see him again. That week Ben Ali was elected to his fifth term, claiming yet another incredible landslide. In January of last year I returned to Tunis as protests against him accelerated. I arranged to interview an opposition activist but couldn't find his party's office, so I called him for directions.

"I'll come outside and meet you," he said.

"No, just tell me how to get there." The police were known to tap phones; the street wasn't safe.

"Don't worry, I'll meet you outside the national conservatory."

I should have insisted. I reached the conservatory and waited. A moment later, I saw the activist shouting as he was dragged off between two large men.

A week later, as he balanced a cigarette between his fine fingers, he told me that the police had handcuffed him to his bed and twice brought him to the interior ministry. Twice he refused the ministry's offer to turn paid informant. The first time, ministry agents stripped, slapped and photographed him; the second time, they tied him up and beat him. He spent a night there, listening to screams. After a week he was released.