The records were handed over last week under a Freedom of Information Act request filed by Salt Lake City attorney Jesse Trentadue, who is seeking evidence for his theory that his brother, Kenneth Trentadue, was murdered in an isolation cell at the Federal Transfer Center in Oklahoma City in August 1995.

Jesse Trentadue believes authorities mistakenly suspected that his brother - a convicted bank robber - was part of a gang that robbed banks to finance attacks on the government, possibly including the April 19, 1995, Oklahoma City bombing that killed 168 people.

Among other things, the documents reveal that the FBI and other law enforcement agencies were investigating evidence of a wider conspiracy in the bombing of the Oklahoma City federal building months after claiming the conspiracy was limited to Timothy McVeigh and Terry Nichols.

The documents, which have been heavily redacted to delete the names of confidential sources and other information, also indicate that investigators looked into McVeigh's attempts to contact a resident of Elohim City, a heavily fortified compound in eastern Oklahoma, in the days prior to the bombing.

Separate documents state that telephone records and confidential informants indicate McVeigh called the Elohim City compound at least twice - on April 5, 1995, and around April 17, 1995. ''McVeigh may have been trying to recruit other individuals to assist him,'' states a document dated Jan. 26, 1996.

Authorities have previously said that McVeigh may have tried to contact Andreas Strassmeier, a German national who was head of security for Elohim City. Strassmeir has denied involvement in the bomb plot.

Another heavily edited memo, dated Jan. 4, 1996, states that someone affiliated with the Southern Poverty Law Center, an Alabama-based civil rights group, was at Elohim City about two weeks before the bombing when one of the Oklahoma bombing suspects allegedly called looking for a co-conspirator.

The name of the caller is blacked out, but the person is described as one of the two indicted defendants in the bombing. McVeigh was executed in 2001 and Nichols is serving state and federal life prisons sentences for the bombing.

Jesse Trentadue had already obtained a copy of that memo, which was released years earlier to a different person who had requested the document.

Local and federal investigations ruled Kenneth Trentadue's death a suicide, although bruises and other marks on his body raised questions among some officials about whether he was murdered or committed suicide.

Kenneth Trentadue, 44, was being held on an alleged parole violation when guards found him dead on Aug. 21, 1995, hanging from a noose made of torn bed sheets.

Prison officials told the family he suffered several injuries when his first hanging attempt failed, before succeeding on a second hanging attempt.

His family insists he was killed and contend correctional officials destroyed evidence. Authorities have denied the allegations. Several investigations also ruled the death a suicide.