Family and colleagues are mourning the death of Northeast Credit Union’s president and chief executive officer, who died in a weekend snowmobile accident. New Hampshire Fish and Game officials said Peter Kavalauskas, 62, of Dover, died after hitting trees on the shore of Millen Lake in Washington, N.H. at about 1 a.m. Saturday. He was pronounced dead at the scene. Authorities said the crash remained under investigation Sunday but believe speed was a contributing factor. The accident happened days after Kavalauskas announced his retirement after nearly 30 years at the credit union’s helm. He joined the company as an associate manager in 1978. There are 15 branches of the credit union, which is based in Portsmouth.