Melissa Gilbert has asked a judge to keep her husband Timothy Busfield "protected" in prison amid his child sex abuse charges.

The Little House on the Prairie star, 61, has expressed her support for her "sweet husband" in a letter to the judge in his case after he turned himself into police earlier this week and was charged with two counts of criminal sexual contact with a minor and one count of child abuse.

Melissa, who has been married to The West Wing actor since 2013, wrote: "The reality is that Tim Busfield is my love, my rock, my partner in business and life. He is my comfort and my council. His joy, humour and quick wit bring sparkle to my life. Tim is, quite simply, the beating heart of our wild and wonderful extended family.

"I can tell you, and anyone, that I know Tim better and more intimately than anything in his life ever has. Conversely, he knows me in the same way.

"Tim has the strongest moral compass of any human I have ever known. He has dedicated his spiritual self to always being of service to others. He starts every day with kindness and compassion."

Melissa explained that "one of the great joys" of her life has been watching Timothy, 68, bond with her youngest son Michael, 30, from her marriage to second husband Bruce Boxleitner.

She wrote: "Michael was a teenager when Tim and I got together. A full-blown, angst-ridden teenager trying to figure out his place in the world.

"Tim nurtured and guided Michael. He admonished, praised, loved, consoled, cajoled, fretted, cared for, and fed my son both physically and spiritually. I will never be able to express the depth of gratitude I have to God for bringing this wonderful human into our lives."

Melissa concluded the note by describing it as "the strangest letter I've ever had to write".

She penned: "I am trying to tow a line between logic and all the feelings swirling through me. I began this letter with logic, but now the feelings have taken over. I can't help it.

"I only want this extraordinary man safe and whole. So, I will close by asking you to please, please, take care of my sweet husband. As he is my protector, I am his, but I cannot protect him now and I think that, more than anything else, is what is truly breaking my heart, I am relying on you to protect him for me."