At first, Fr. William Bowdern, S.J. (and here)expected to drive out the demon with a few simple prayers but he quickly realised that he was up against a powerful foe. Every time Richard tried to say a prayer and renounce Satan, a force would seize control of his body and prevent him from doing so. During the exorcism rituals, Richard became enormously strong and it took three men to pin him down.Father Bowden battled the demon for day after day with Richard continuously taunting him and spitting at his helpers. At one stage the boy grabbed a pen off Father Bowdern and scrawled: "I am the Devil himself".After 28 days, an exhausted Father Bowden tried once again to exorcise Richard and drive out the Devil. But this time was to be different. As Richard struggled to say the Lord's Prayer, a new force seized his body and helped him utter the words needed to expel Satan. Richard was free at last. Later, Richard said that the archangel Michael had intervened to help him say the prayer. He apparantly also saw a vision of the saint battling Satan at the mouth of a burning cave.
A great link with lots of pictures (here)
In a 1988 interview with the St. Louis Post-Dispatch daily newspaper, Father Halloran said he observed streaks and arrows and words like "hell" that would rise on the boy's skin. "The little boy would go into a seizure and get quite violent," Father Halloran recalled. "So Father Bowdern asked me to hold him. Yes, he did break my nose." The exorcism was performed with the approval of Cardinal Lawrence Ritter of St. Louis. Father Halloran would not presume that the boy's actions were caused by demonic possession. "I've withheld judgment," he said. Link (here)