A former child TV star accused of launching a campaign to destroy a venture fund owned by billionaire Peter Thiel deleted nearly 2,000 texts from her company phone, court documents claim.

Crystal McKellar, who played Becky Slater on The Wonder Years in the 1980s and early 90s, become a Harvard-trained lawyer after her TV days were over.

Graduating from Harvard Law School in 2003, she went on to become in house counsel for a Texas venture capital firm.

McKellar, whose sister Danica played Winnie Cooper in the hit show, allegedly tried to undermine Thiel's Mithril Capital Management by writing a number of inflammatory, anonymous handwritten letters to its investors.

She is being sued as part of a breach of contract lawsuit in Delaware, claiming more than $1 million in damages.

It has now emerged the 43-year-old also deleted a total of 1,941 text messages in the eight months before she handed in her work phone, according to court papers. 

Crystal McKellar at The Hamptons International Film Festival Independents Ball at 21 Water yesterday. She has been accused of trying to undermine billionaire Peter Thiel's venture fund company with anonymous letters to its investors 

Entrepreneur and venture capitalist Peter Thiel at Fox News in August. He claims McKellar tried to undermine his company with a letter-writing campaign

Between February when McKellar left the firm and the phone being returned to the firm in September, a tranche of messages were erased and contained only 32 undeleted texts, court papers claim.

The suit states: 'Shockingly, Ms McKellar deleted nearly all of the text messages sent to or from her Mithril Capital Management cellular telephone, despite knowing that Mithril Capital Management was investigating her material breach of her agreements', the New York Post reports.   

The venture fund's follow-up suit in Delaware court accuses McKellar of the 'unauthorized removal, destruction, and attempted destruction of Mithril records and property'.

McKellar's letters accused Mithril co-founder Ajay Royan of 'lying to investors and the public about how much he is charging us in management fees'. 

She previously told Fox News the allegations of wrongdoing were 'unequivocally false'. 

Crystal McKellar and her sister Danica in the early 1990s when they were both on the hit show The Wonder Years. Crystal is facing a $1bn lawsuit over breach of contract allegations from her former employer 

McKellar added: 'I left Mithril earlier this year when it became clear to me that Mithril's leadership was lying to its investors and that the promises it had made were not going to be kept.' 

The former actress worked as the only general counsel of Mithril until February of this year and left the firm with a $225,000-a-year consulting job, according to a suit filed this week in Texas state court.

After leaving, she is accused of immediately beginning 'a concerted whisper campaign to undermine Mithril, in which she would make false, anonymous complaints to Mithril's limited partners'. 

The suit alleges McKellar attempted to 'solicit Mithril's limited partners almost immediately' claiming that her former firm was being investigated by US regulators. 

McKellar is also alleged to have mailed letters 'written to sow discord between Mithril and its business partners'.

Mithril stated how the firm was charging appropriate fees which McKellar herself had signed off on, according to the suit.