Annie Tomasini became the third Biden administration official to plead the Fifth Amendment in a House panel's investigation into the former president's mental fitness.

House Oversight Chair says that former VP Harris and Jill Biden “should” be subpoenaed in the panel’s investigation into former President Joe Biden’s mental capacity.

Former President Joe Biden, in an interview with the New York Times, said that he personally made every clemency and pardon decision during the end of his presidency.

President Donald Trump responded to comments that former President Joe Biden made in a recent interview with The New York Times.

Dr. Kevin O'Connor, former President Joe Biden's physician, pleaded the Fifth during a brief appearance before the House Oversight Committee for a closed interview.

Dr. Kevin O'Connor, former President Joe Biden's physician, pleaded the Fifth during a brief appearance before the House Oversight Committee for a closed interview.

Former President Joe Biden has been diagnosed with prostate cancer, according to a statement from his office released Sunday afternoon.

House Oversight Committee’s first closed-door meeting investigating former President Biden's mental acuity begins with former aide Neera Tanden appearing for questioning.

The Senate Judiciary Committee is holding a hearing Wednesday examining the cognitive abilities of former President Joe Biden.

President Trump doubled down on his accusations that former President Joe Biden was mentally unfit and not running the country, but provided no evidence.

In a bilateral meeting, President Trump brought up his criticism about former President Biden and the alleged use of an autopen to sign documents during Biden's presidency.

Bill Clinton, on ABC's "The View," said he did not have concerns about former President Joe Biden's mental health and wants Democrats to focus on the future.

Bill Clinton, on ABC's "The View," said he did not have concerns about former President Joe Biden's mental health and wants Democrats to focus on the future.

The move by the White House represents a significant escalation, as it is a directive to the Justice Department to formally investigate.

President Donald Trump is ordering the Justice Department to investigate the final years of former President Joe Biden's presidency.

Former White House press secretary Karine Jean-Pierre has left the Democratic Party and is now an independent, according to a press release announcing her new book.

Earlier this month, the former president was diagnosed with an aggressive form of prostate cancer.

The hearing, slated for next month, will investigate "who was running the country" during Biden's "decline."

Former President Joe Biden highlighted the 10th anniversary of the passing of his son Beau – who served in the Delaware Army National Guard and died of brain cancer on May 30, 2015.

He spoke to reporters about his treatment after a veterans memorial event in Delaware.

Republican Rep. James Comer is requesting former White House physician, Kevin O'Connor, appear for a transcribed interview as part of a probe into Biden's mental fitness.

Experts say PSA tests are typically not recommended for men older than 70.

A spokesperson for the former president addressed Joe Biden's history with PSA tests and revealed he received his last blood test in 2014.

A spokesperson for the former president addressed Joe Biden's history with PSA tests and revealed he received his last blood test in 2014.

In a copy of “Original Sin” obtained by ABC News, journalists Jake Tapper and Alex Thompson allege Joe Biden hid info about his son Beau's cancer diagnosis.

Biden, even after he has exited political life and as he faces a serious cancer diagnosis, remains a factor in the conversation about his party's political future.

ABC News’ Averi Harper reports on the legacy of former President Joe Biden, as well as political reaction to his cancer diagnosis.

Former President Joe Biden's cancer diagnosis is drawing new questions about his health while in the White House.

Former President Joe Biden has been diagnosed with an aggressive form of prostate cancer that has metastasized to the bone, his office announced this week.

ABC News’ Linsey Davis speaks with Sloan Kettering’s prostate cancer section head, Dr. Michael J. Morris, on what former President Biden’s cancer diagnosis means and what treatment may look like.

Biden, 82, left office as the oldest serving president in U.S. history.

After revealing he's been diagnosed with prostate cancer, former Pres. Biden shared a new photo with former first lady Jill Biden, writing, "Cancer touches us all."

President Trump called former President Joe Biden's cancer diagnosis "very sad" before speculating about the timing of Biden's public disclosure of the disease.

ABC News medical correspondent Dr. Darien Sutton shares the possible timeline of former President Joe Biden’s diagnosis.

Experts told ABC News it’s not uncommon for older prostate cancer patients, like former President Joe Biden, to receive a diagnosis when the disease is advanced.

Former President Joe Biden's office announced on Sunday that he was diagnosed with an "aggressive" form of prostate cancer. Here's what to know about the disease.

ABC News' Dr. Darien Sutton breaks down what to know about former President Joe Biden’s “aggressive” cancer diagnosis.

Former President Joe Biden had previously led the federal government's effort to "end cancer as we know it" through a cancer "moonshot" initiative.

The book, “Original Sin,” outlines new claims about former President Joe Biden’s physical and mental health and follows Biden's announcement of a prostate cancer diagnosis.

Arif Kamal, chief patient officer at the American Cancer Society, discusses former President Joe Biden's prostate cancer diagnosis.

Dr. Khurshid Guru, a urological surgeon at Roswell Park Comprehensive Cancer Center, shares what men should ask their doctors about the disease.

A newly released audio clip appears to show former President Joe Biden struggling to recall the dates of key events in his life, including the death of his son Beau.

Former President Joe Biden has been diagnosed with an "aggressive" form of prostate cancer that has been characterized by a "Gleason score of 9" and includes metastasis to the bone, his office said.

Amid news of former President Joe Biden’s prostate cancer diagnosis, ABC News Chief Medical Correspondent Dr. Tara Narula breaks down what his condition means and what possible treatments can be done.

Former President Joe Biden's office shared his prostate cancer diagnosis Sunday. He was diagnosed May 16.

A statement from his office announced on Sunday that Biden has been diagnosed with 'aggressive' prostate cancer.

ABC News has broken down what former President Biden's prostate cancer diagnosis means and what possible treatments can be done.

ABC News’ Jonathan Karl interviews Rep. Ro Khanna, D-Calif., on “This Week.”

Former President Joe Biden's office said Sunday he recently began experiencing symptoms and was diagnosed with an aggressive form of prostate cancer on May 16.

Dr. Stephanie Widmer, an emergency medical physician, joined ABC News Live to discuss potential diagnoses and treatment for former President Joe Biden, who has been diagnosed with prostate cancer.